Prior to this commit, when the sending client overshot RabbitMQ's incoming-window
(which is allowed in the event of a cluster wide memory or disk alarm),
and RabbitMQ sent a FLOW frame to the client, RabbitMQ sent a negative
incoming-window field in the FLOW frame causing the following crash in
the writer proc:
```
crasher:
initial call: rabbit_amqp_writer:init/1
pid: <0.19353.0>
registered_name: []
exception error: bad argument
in function iolist_size/1
called as iolist_size([<<112,0,0,23,120>>,
[82,-15],
<<"pÿÿÿü">>,<<"pÿÿÿÿ">>,67,
<<112,0,0,23,120>>,
"Rª",64,64,64,64])
*** argument 1: not an iodata term
in call from amqp10_binary_generator:generate1/1 (amqp10_binary_generator.erl, line 141)
in call from amqp10_binary_generator:generate1/1 (amqp10_binary_generator.erl, line 88)
in call from amqp10_binary_generator:generate/1 (amqp10_binary_generator.erl, line 79)
in call from rabbit_amqp_writer:assemble_frame/3 (rabbit_amqp_writer.erl, line 206)
in call from rabbit_amqp_writer:internal_send_command_async/3 (rabbit_amqp_writer.erl, line 189)
in call from rabbit_amqp_writer:handle_cast/2 (rabbit_amqp_writer.erl, line 110)
in call from gen_server:try_handle_cast/3 (gen_server.erl, line 1121)
```
This commit fixes this crash by maintaning a floor of zero for
incoming-window in the FLOW frame.
Fixes#12816
Introduce a single place in the AMQP 1.0 Erlang client that infers the AMQP 1.0 type.
Erlang integers are inferred to be AMQP type `long` to avoid overflow surprises.
Provides a specific function to fix client ssl options, i.e.: apply all
fixes that are applied for TLS listeneres and clients on previous
versions but also sets `cacerts` option to CA certificates obtained by
`public_key:cacerts_get`, only when no `cacertfile` or `cacerts` are
provided.
This commit notifies the client app with the AMQP performative if
connection config `notify_with_performative` is set to `true`.
This allows the client app to learn about all fields including
properties and capabilities returned by the AMQP server.
Support tracking the requeue history as described in
https://github.com/rabbitmq/rabbitmq-website/pull/2095
This commit:
1. adds a test case tracing the requeue history via AMQP 1.0
using the modified outcome and
2. fixes bugs in the broker which crashed if a modified message
annotation value is an AMQP 1.0 list, map, or array.
Complex modified annotation values (list, map, array) are stored as tagged values from now on.
This means AMQP 0.9.1 consumers will not receive modified annotations of
type list, map, or array (which is okay).
* Support AMQP filter expressions
## What?
This PR implements the following property filter expressions for AMQP clients
consuming from streams as defined in
[AMQP Filter Expressions Version 1.0 Working Draft 09](https://groups.oasis-open.org/higherlogic/ws/public/document?document_id=66227):
* properties filters [section 4.2.4]
* application-properties filters [section 4.2.5]
String prefix and suffix matching is also supported.
This PR also fixes a bug where RabbitMQ would accept wrong filters.
Specifically, prior to this PR the values of the filter-set's map were
allowed to be symbols. However, "every value MUST be either null or of a
described type which provides the archetype filter."
## Why?
This feature adds the ability to RabbitMQ to have multiple concurrent clients
each consuming only a subset of messages while maintaining message order.
This feature also reduces network traffic between RabbitMQ and clients by
only dispatching those messages that the clients are actually interested in.
Note that AMQP filter expressions are more fine grained than the [bloom filter based
stream filtering](https://www.rabbitmq.com/blog/2023/10/16/stream-filtering) because
* they do not suffer false positives
* the unit of filtering is per-message instead of per-chunk
* matching can be performed on **multiple** values in the properties and
application-properties sections
* prefix and suffix matching on the actual values is supported.
Both, AMQP filter expressions and bloom filters can be used together.
## How?
If a filter isn't valid, RabbitMQ ignores the filter. RabbitMQ only
replies with filters it actually supports and validated successfully to
comply with:
"The receiving endpoint sets its desired filter, the sending endpoint
[RabbitMQ] sets the filter actually in place (including any filters defaulted at
the node)."
* Delete streams test case
The test suite constructed a wrong filter-set.
Specifically the value of the filter-set didn't use a described type as
mandated by the spec.
Using https://azure.github.io/amqpnetlite/api/Amqp.Types.DescribedValue.html
throws errors that the descriptor can't be encoded. Given that this code
path is already tests via the amqp_filtex_SUITE, this F# test gets
therefore deleted.
* Re-introduce the AMQP filter-set bug
Since clients might rely on the wrong filter-set value type, we support
the bug behind a deprecated feature flag and gradually remove support
this bug.
* Revert "Delete streams test case"
This reverts commit c95cfeaef7.
For messages published to RabbitMQ, RabbitMQ honors the transfer `settled`
field, no matter what value the sender settle mode was set to in the attach
frame.
Therefore, prior to this commit, a client could send a transfer with
`settled=true` even though sender settle mode was set to `unsettled` in the
attach frame.
This commit enforces that the publisher sets only transfer `settled` fields
that are valid with the spec.
If sender settle mode is:
* `unsettled`, the transfer `settled` flag must be `false`.
* `settled`, the transfer `settled` flag must be `true`.
* `mixed`, the transfer `settled` flag can be `true` or `false`.
```
<field name="message-annotations" type="fields"/>
```
Prior to this commit integration tests succeeded because both Erlang
client and RabbitMQ server contained a bug.
This bug was noticed by a Java client test suite.
* Enforce AMQP 1.0 channel-max
Enforce AMQP 1.0 field `channel-max` in the `open` frame by introducing
a new more user friendly setting called `session_max`:
> The channel-max value is the highest channel number that can be used on the connection.
> This value plus one is the maximum number of sessions that can be simultaneously active on the connection.
We set the default value of `session_max` to 64 such that, by
default, RabbitMQ 4.0 allows maximum 64 AMQP 1.0 sessions per AMQP 1.0 connection.
More than 64 AMQP 1.0 sessions per connection make little sense.
See also https://www.rabbitmq.com/blog/2024/09/02/amqp-flow-control#session
Limiting the maximum number of sessions per connection can be useful to
protect against
* applications that accidentally open new sessions without ending old sessions
(session leaks)
* too many metrics being exposed, for example in the future via the
"/metrics/per-object" Prometheus endpoint with timeseries per session
being emitted.
This commit does not make use of the existing `channel_max` setting
because:
1. Given that `channel_max = 0` means "no limit", there is no way for an
operator to limit the number of sessions per connections to 1.
2. Operators might want to set different limits for maximum number of
AMQP 0.9.1 channels and maximum number of AMQP 1.0 sessions.
3. The default of `channel_max` is very high: It allows using more than
2,000 AMQP 0.9.1 channels per connection. Lowering this default might
break existing AMQP 0.9.1 applications.
This commit also fixes a bug in the AMQP 1.0 Erlang client which, prior
to this commit used channel number 1 for the first session. That's wrong
if a broker allows maximum 1 session by replying with `channel-max = 0`
in the `open` frame. Additionally, the spec recommends:
> To make it easier to monitor AMQP sessions, it is RECOMMENDED that implementations always assign the lowest available unused channel number.
Note that in AMQP 0.9.1, channel number 0 has a special meaning:
> The channel number is 0 for all frames which are global to the connection and 1-65535 for frames that
refer to specific channels.
* Apply PR feedback
This has no real impact on performance[1] but should
make it clear which application can run the broker
and/or publish to Hex.pm. In particular, applications
that we can't run the broker from will now give up
early if we try to.
Note that while the broker can't normally run from the
amqp_client application's directory, it can run from
tests and some of the tests start the broker.
[1] on my machine
No real need to have two files, especially since it contains
only a few variable definitions. Plan is to only keep
separate files for larger features such as dist or run.
## 1. Introduce new SASL mechanism ANONYMOUS
### What?
Introduce a new `rabbit_auth_mechanism` implementation for SASL
mechanism ANONYMOUS called `rabbit_auth_mechanism_anonymous`.
### Why?
As described in AMQP section 5.3.3.1, ANONYMOUS should be used when the
client doesn't need to authenticate.
Introducing a new `rabbit_auth_mechanism` consolidates and simplifies how anonymous
logins work across all RabbitMQ protocols that support SASL. This commit
therefore allows AMQP 0.9.1, AMQP 1.0, stream clients to connect out of
the box to RabbitMQ without providing any username or password.
Today's AMQP 0.9.1 and stream protocol client libs hard code RabbitMQ default credentials
`guest:guest` for example done in:
* 0215e85643/src/main/java/com/rabbitmq/client/ConnectionFactory.java (L58-L61)
* ddb7a2f068/uri.go (L31-L32)
Hard coding RabbitMQ specific default credentials in dozens of different
client libraries is an anti-pattern in my opinion.
Furthermore, there are various AMQP 1.0 and MQTT client libraries which
we do not control or maintain and which still should work out of the box
when a user is getting started with RabbitMQ (that is without
providing `guest:guest` credentials).
### How?
The old RabbitMQ 3.13 AMQP 1.0 plugin `default_user`
[configuration](146b4862d8/deps/rabbitmq_amqp1_0/Makefile (L6))
is replaced with the following two new `rabbit` configurations:
```
{anonymous_login_user, <<"guest">>},
{anonymous_login_pass, <<"guest">>},
```
We call it `anonymous_login_user` because this user will be used for
anonymous logins. The subsequent commit uses the same setting for
anonymous logins in MQTT. Hence, this user is orthogonal to the protocol
used when the client connects.
Setting `anonymous_login_pass` could have been left out.
This commit decides to include it because our documentation has so far
recommended:
> It is highly recommended to pre-configure a new user with a generated username and password or delete the guest user
> or at least change its password to reasonably secure generated value that won't be known to the public.
By having the new module `rabbit_auth_mechanism_anonymous` internally
authenticate with `anonymous_login_pass` instead of blindly allowing
access without any password, we protect operators that relied on the
sentence:
> or at least change its password to reasonably secure generated value that won't be known to the public
To ease the getting started experience, since RabbitMQ already deploys a
guest user with full access to the default virtual host `/`, this commit
also allows SASL mechanism ANONYMOUS in `rabbit` setting `auth_mechanisms`.
In production, operators should disable SASL mechanism ANONYMOUS by
setting `anonymous_login_user` to `none` (or by removing ANONYMOUS from
the `auth_mechanisms` setting. This will be documented separately.
Even if operators forget or don't read the docs, this new ANONYMOUS
mechanism won't do any harm because it relies on the default user name
`guest` and password `guest`, which is recommended against in
production, and who by default can only connect from the local host.
## 2. Require SASL security layer in AMQP 1.0
### What?
An AMQP 1.0 client must use the SASL security layer.
### Why?
This is in line with the mandatory usage of SASL in AMQP 0.9.1 and
RabbitMQ stream protocol.
Since (presumably) any AMQP 1.0 client knows how to authenticate with a
username and password using SASL mechanism PLAIN, any AMQP 1.0 client
also (presumably) implements the trivial SASL mechanism ANONYMOUS.
Skipping SASL is not recommended in production anyway.
By requiring SASL, configuration for operators becomes easier.
Following the principle of least surprise, when an an operator
configures `auth_mechanisms` to exclude `ANONYMOUS`, anonymous logins
will be prohibited in SASL and also by disallowing skipping the SASL
layer.
### How?
This commit implements AMQP 1.0 figure 2.13.
A follow-up commit needs to be pushed to `v3.13.x` which will use SASL
mechanism `anon` instead of `none` in the Erlang AMQP 1.0 client
such that AMQP 1.0 shovels running on 3.13 can connect to 4.0 RabbitMQ nodes.
* Support SASL mechanism EXTERNAL in Erlang AMQP 1.0 client
* Move test to plugin rabbitmq_auth_mechanism_ssl
In theory, there can be other plugin that offer SASL mechanism EXTERNAL.
Therefore, instead of adding a test dependency from app rabbit to app
rabbitmq_auth_mechanism_ssl, it's better to test this plugin specific
functionality directly in the plugin itself.
This commit contains the following new quorum queue features:
* Fair share high/low priorities
* SAC consumers honour consumer priorities
* Credited consumer refactoring to meet AMQP requirements.
* Use checkpoints feature to reduce memory use for queues with long backlogs
* Consumer cancel option that immediately removes consumer and returns all pending messages.
* More compact commands of the most common commands such as enqueue, settle and credit
* Correctly track the delivery-count to be compatible with the AMQP spec
* Support the "modified" AMQP 1.0 outcome better.
Commits:
* Quorum queues v4 scaffolding.
Create the new version but not including any changes yet.
QQ: force delete followers after leader has terminated.
Also try a longer sleep for mqtt_shared_SUITE so that the
delete operation stands a chance to time out and move on
to the forced deletion stage.
In some mixed machine version scenarios some followers will never
apply the poison pill command so we may as well force delete them
just in case.
QQ: skip test in amqp_client that cannot pass with mixed machine versions
QQ: remove dead code
Code relating to prior machine versions and state conversions.
rabbit_fifo_prop_SUITE fixes
* QQ: add v4 ff and new more compact enqueue command.
Also update rabbit_fifo_* suites to test more relevant code versions
where applicable.
QQ: always use the updated credit mode format
QQv4: use more compact consumer reference in settle, credit, return
This introudces a new type: consumer_key() which is either the consumer_id
or the raft index the checkout was processed at. If the consumer is
using one of the updated credit spec formats rabbit_fifo will use the
raft index as the primary key for the consumer such that the rabbit
fifo client can then use the more space efficient integer index
instead of the full consumer id in subsequent commands.
There is compatibility code to still accept the consumer id in
settle, return, discard and credit commands but this is slighlyt
slower and of course less space efficient.
The old form will be used in cases where the fifo client may have
already remove the local consumer state (as happens after a cancel).
Lots of test refactorings of the rabbit_fifo_SUITE to begin to use
the new forms.
* More test refactoring and new API fixes
rabbit_fifo_prop_SUITE refactoring and other fixes.
* First pass SAC consumer priority implementation.
Single active consumers will be activated if they have a higher priority
than the currently active consumer. if the currently active consumer
has pending messages, no further messages will be assigned to the
consumer and the activation of the new consumer will happen once
all pending messages are settled. This is to ensure processing order.
Consumers with the same priority will internally be ordered to
favour those with credit then those that attached first.
QQ: add SAC consumer priority integration tests
QQ: add check for ff in tests
* QQ: add new consumer cancel option: 'remove'
This option immediately removes and returns all messages for a
consumer instead of the softer 'cancel' option which keeps the
consumer around until all pending messages have been either
settled or returned.
This involves a change to the rabbit_queue_type:cancel/5 API
to rabbit_queue_type:cancel/3.
* QQ: capture checked out time for each consumer message.
This will form the basis for queue initiated consumer timeouts.
* QQ: Refactor to use the new ra_machine:handle_aux/5 API
Instead of the old ra_machine:handle_aux/6 callback.
* QQ hi/lo priority queue
* QQ: Avoid using mc:size/1 inside rabbit_fifo
As we dont want to depend on external functions for things that may
change the state of the queue.
* QQ bug fix: Maintain order when returning multiple
Prior to this commit, quorum queues requeued messages in an undefined
order, which is wrong.
This commit fixes this bug and requeues messages always in the order as
nacked / rejected / released by the client.
We ensure that order of requeues is deterministic from the client's
point of view and doesn't depend on whether the quorum queue soft limit
was exceeded temporarily.
So, even when rabbit_fifo_client batches requeues, the order as nacked
by the client is still maintained.
* Simplify
* Add rabbit_quorum_queue:file_handle* functions back.
For backwards compat.
* dialyzer fix
* dynamic_qq_SUITE: avoid mixed versions failure.
* QQ: track number of requeues for message.
To be able to calculate the correct value for the AMQP delivery_count
header we need to be able to distinguish between messages that were
"released" or returned in QQ speak and those that were returned
due to errors such as channel termination.
This commit implement such tracking as well as the calculation
of a new mc annotations `delivery_count` that AMQP makes use
of to set the header value accordingly.
* Use QQ consumer removal when AMQP client detaches
This enables us to unskip some AMQP tests.
* Use AMQP address v2 in fsharp-tests
* QQ: track number of requeues for message.
To be able to calculate the correct value for the AMQP delivery_count
header we need to be able to distinguish between messages that were
"released" or returned in QQ speak and those that were returned
due to errors such as channel termination.
This commit implement such tracking as well as the calculation
of a new mc annotations `delivery_count` that AMQP makes use
of to set the header value accordingly.
* rabbit_fifo: Use Ra checkpoints
* quorum queues: Use a custom interval for checkpoints
* rabbit_fifo_SUITE: List actual effects in ?ASSERT_EFF failure
* QQ: Checkpoints modifications
* fixes
* QQ: emit release cursors on tick for followers and leaders
else followers could end up holding on to segments a bit longer
after traffic stops.
* Support draining a QQ SAC waiting consumer
By issuing drain=true, the client says "either send a transfer or a flow frame".
Since there are no messages to send to an inactive consumer, the sending
queue should advance the delivery-count consuming all link-credit and send
a credit_reply with drain=true to the session proc which causes the session
proc to send a flow frame to the client.
* Extract applying #credit{} cmd into 2 functions
This commit is only refactoring and doesn't change any behaviour.
* Fix default priority level
Prior to this commit, when a message didn't have a priority level set,
it got enqueued as high prio.
This is wrong because the default priority is 4 and
"for example, if 2 distinct priorities are implemented,
then levels 0 to 4 are equivalent, and levels 5 to 9 are equivalent
and levels 4 and 5 are distinct."
Hence, by default a message without priority set, must be enqueued as
low prio.
* bazel run gazelle
* Avoid deprecated time unit
* Fix aux_test
* Delete dead code
* Fix rabbit_fifo_q:get_lowest_index/1
* Delete unused normalize functions
* Generate less garbage
* Add integration test for QQ SAC with consumer priority
* Improve readability
* Change modified outcome behaviour
With the new quorum queue v4 improvements where a requeue counter was
added in addition to the quorum queue delivery counter, the following
sentence from https://github.com/rabbitmq/rabbitmq-server/pull/6292#issue-1431275848
doesn't apply anymore:
> Also the case where delivery_failed=false|undefined requires the release of the
> message without incrementing the delivery_count. Again this is not something
> that our queues are able to do so again we have to reject without requeue.
Therefore, we simplify the modified outcome behaviour:
RabbitMQ will from now on only discard the message if the modified's
undeliverable-here field is true.
* Introduce single feature flag rabbitmq_4.0.0
## What?
Merge all feature flags introduced in RabbitMQ 4.0.0 into a single
feature flag called rabbitmq_4.0.0.
## Why?
1. This fixes the crash in
https://github.com/rabbitmq/rabbitmq-server/pull/10637#discussion_r1681002352
2. It's better user experience.
* QQ: expose priority metrics in UI
* Enable skipped test after rebasing onto main
* QQ: add new command "modify" to better handle AMQP modified outcomes.
This new command can be used to annotate returned or rejected messages.
This commit also retains the delivery-count across dead letter boundaries
such that the AMQP header delivery-count field can now include _all_ failed
deliver attempts since the message was originally received.
Internally the quorum queue has moved it's delivery_count header to
only track the AMQP protocol delivery attempts and now introduces
a new acquired_count to track all message acquisitions by consumers.
* Type tweaks and naming
* Add test for modified outcome with classic queue
* Add test routing on message-annotations in modified outcome
* Skip tests in mixed version tests
Skip tests in mixed version tests because feature flag
rabbitmq_4.0.0 is needed for the new #modify{} Ra command
being sent to quorum queues.
---------
Co-authored-by: David Ansari <david.ansari@gmx.de>
Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
Arguments
* `rabbitmq:stream-offset-spec`,
* `rabbitmq:stream-filter`,
* `rabbitmq:stream-match-unfiltered`
are set in the `filter` field of the `Source`.
This makes sense for these consumer arguments because:
> A filter acts as a function on a message which returns a boolean result
> indicating whether the message can pass through that filter or not.
Consumer priority is not really such a predicate.
Therefore, it makes more sense to set consumer priority in the
`properties` field of the `Attach` frame.
We call the key `rabbitmq:priority` which maps to consumer argument
`x-priority`.
While AMQP 0.9.1 consumers are allowed to set any integer data
type for the priority level, this commit decides to enforce an `int`
value (range -(2^31) to 2^31 - 1 inclusive).
Consumer priority levels outside of this range are not needed in
practice.
We don't need to duplicate so many patterns in so many
files since we have a monorepo (and want to keep it).
If I managed to miss something or remove something that
should stay, please put it back. Note that monorepo-wide
patterns should go in the top-level .gitignore file.
Other .gitignore files are for application or folder-
specific patterns.
Since OTP 26 the verify_peer TLS option is enabled by default, which
requires to specify cacerts as well. This change helps with not having
to specify TLS options like cacertfile at every connection. This is
especially helpful for shovels using AMQP 1.0, where the TLS options
would otherwise need to be specified as URI parameters. Similar env
configuration already exists for amqp_client.
## What?
Introduce RabbitMQ internal flow control for messages sent to AMQP
clients.
Prior this PR, when an AMQP client granted a large amount of link
credit (e.g. 100k) to the sending queue, the sending queue sent
that amount of messages to the session process no matter what.
This becomes problematic for memory usage when the session process
cannot send out messages fast enough to the AMQP client, especially if
1. The writer proc cannot send fast enough. This can happen when
the AMQP client does not receive fast enough and causes TCP
back-pressure to the server. Or
2. The server session proc is limited by remote-incoming-window.
Both scenarios are now added as test cases.
Tests
* tcp_back_pressure_rabbitmq_internal_flow_quorum_queue
* tcp_back_pressure_rabbitmq_internal_flow_classic_queue
cover scenario 1.
Tests
* incoming_window_closed_rabbitmq_internal_flow_quorum_queue
* incoming_window_closed_rabbitmq_internal_flow_classic_queue
cover scenario 2.
This PR sends messages from queues to AMQP clients in a more controlled
manner.
To illustrate:
```
make run-broker PLUGINS="rabbitmq_management" RABBITMQ_SERVER_ADDITIONAL_ERL_ARGS="+S 4"
observer_cli:start()
mq
```
where `mq` sorts by message queue length.
Create a stream:
```
deps/rabbitmq_management/bin/rabbitmqadmin declare queue name=s1 queue_type=stream durable=true
```
Next, send and receive from the Stream via AMQP.
Grant a large number of link credit to the sending stream:
```
docker run -it --rm --add-host host.docker.internal:host-gateway ssorj/quiver:latest
bash-5.1# quiver --version
quiver 0.4.0-SNAPSHOT
bash-5.1# quiver //host.docker.internal//queue/s1 --durable -d 30s --credit 100000
```
**Before** to this PR:
```
RESULTS
Count ............................................... 100,696 messages
Duration ............................................... 30.0 seconds
Sender rate ......................................... 120,422 messages/s
Receiver rate ......................................... 3,363 messages/s
End-to-end rate ....................................... 3,359 messages/s
```
We observe that all 100k link credit worth of messages are buffered in the
writer proc's mailbox:
```
|No | Pid | MsgQueue |Name or Initial Call | Memory | Reductions |Current Function |
|1 |<0.845.0> |100001 |rabbit_amqp_writer:init/1 | 126.0734 MB| 466633491 |prim_inet:send/5 |
```
**After** to this PR:
```
RESULTS
Count ............................................. 2,973,440 messages
Duration ............................................... 30.0 seconds
Sender rate ......................................... 123,322 messages/s
Receiver rate ........................................ 99,250 messages/s
End-to-end rate ...................................... 99,148 messages/s
```
We observe that the message queue lengths of both writer and session
procs are low.
## How?
Our goal is to have queues send out messages in a controlled manner
without overloading RabbitMQ itself.
We want RabbitMQ internal flow control between:
```
AMQP writer proc <--- session proc <--- queue proc
```
A similar concept exists for classic queues sending via AMQP 0.9.1.
We want an approach that applies to AMQP and works generic for all queue
types.
For the interaction between AMQP writer proc and session proc we use a
simple credit based approach reusing module `credit_flow`.
For the interaction between session proc and queue proc, the following options
exist:
### Option 1
The session process provides expliclity feedback to the queue after it
has sent N messages.
This approach is implemented in
https://github.com/ansd/rabbitmq-server/tree/amqp-flow-control-poc-1
and works well.
A new `rabbit_queue_type:sent/4` API was added which lets the queue proc know
that it can send further messages to the session proc.
Pros:
* Will work equally well for AMQP 0.9.1, e.g. when quorum queues send messages
in auto ack mode to AMQP 0.9.1 clients.
* Simple for the session proc
Cons:
* Sligthly added complexity in every queue type implementation
* Multiple Ra commands (settle, credit, sent) to decide when a quorum
queue sends more messages.
### Option 2
A dual link approach where two AMQP links exists between
```
AMQP client <---link--> session proc <---link---> queue proc
```
When the client grants a large amount of credits, the session proc will
top up credits to the queue proc periodically in smaller batches.
Pros:
* No queue type modifications required.
* Re-uses AMQP link flow control
Cons:
* Significant added complexity in the session proc. A client can
dynamically decrease or increase credits and dynamically change the drain
mode while the session tops up credit to the queue.
### Option 3
Credit is a 32 bit unsigned integer.
The spec mandates that the receiver independently chooses a credit.
Nothing in the spec prevents the receiver to choose a credit of 1 billion.
However the credit value is merely a **maximum**:
> The link-credit variable defines the current maximum legal amount that the delivery-count can be increased by.
Therefore, the server is not required to send all available messages to this
receiver.
For delivery-count:
> Only the sender MAY independently modify this field.
"independently" could be interpreted as the sender could add to the delivery-count
irrespective of what the client chose for drain and link-credit.
Option 3: The queue proc could at credit time already consume credit
and advance the delivery-count if credit is too large before checking out any messages.
For example if credit is 100k, but the queue only wants to send 1k, the queue could
consume 99k of credits and advance the delivery-count, and subsequently send maximum 1k messages.
If the queue advanced the delivery-count, RabbitMQ must send a FLOW to the receiver,
otherwise the receiver wouldn’t know that it ran out of link-credit.
Pros:
* Very simple
Cons:
* Possibly unexpected behaviour for receiving AMQP clients
* Possibly poor end-to-end throughput in auto-ack mode because the queue
would send a batch of messages followed by a FLOW containing the advanced
delivery-count. Only therafter the client will learn that it ran out of
credits and top-up again. This feels like synchronously pulling a batch
of messages. In contrast, option 2 sends out more messages as soon as
the previous messages left RabbitMQ without requiring again a credit top
up from the receiver.
* drain mode with large credits requires the queue to send all available
messages and only thereafter advance the delivery-count. Therefore,
drain mode breaks option 3 somewhat.
### Option 4
Session proc drops message payload when its outgoing-pending queue gets
too large and re-reads payloads from the queue once the message can be
sent (see `get_checked_out` Ra command for quorum queues).
Cons:
* Would need to be implemented for every queue type, especially classic queues
* Doesn't limit the amount of message metadata in the session proc's
outgoing-pending queue
### Decision: Option 2
This commit implements option 2 to avoid any queue type modification.
At most one credit request is in-flight between session process and
queue process for a given queue consumer.
If the AMQP client sends another FLOW in between, the session proc
stashes the FLOW until it processes the previous credit reply.
A delivery is only sent from the outgoing-pending queue if the
session proc is not blocked by
1. writer proc, or
2. remote-incoming-window
The credit reply is placed into the outgoing-pending queue.
This ensures that the session proc will only top up the next batch of
credits if sufficient messages were sent out to the writer proc.
A future commit could additionally have each queue limit the number of
unacked messages for a given AMQP consumer, or alternatively make use
of session outgoing-window.
Prior to this commit the entire amqp-value or amqp-sequence sections
were parsed when converting a message from mc_amqp.
Parsing the entire amqp-value or amqp-sequence section can generate a
huge amount of garbage depending on how large these sections are.
Given that other protocol cannot make use of amqp-value and
amqp-sequence sections anyway, leave them AMQP encoded when converting
from mc_amqp.
In fact prior to this commit, the entire body section was parsed
generating huge amounts of garbage just to subsequently encode it again
in mc_amqpl or mc_mqtt.
The new conversion interface from mc_amqp to other mc_* modules will
either output amqp-data sections or the encoded amqp-value /
amqp-sequence sections.
This commit enables client apps to automatically perform end-to-end
checksumming over the bare message (i.e. body + application defined
headers).
This commit allows an app to configure the AMQP client:
* for a sending link to automatically compute CRC-32 or Adler-32
checksums over each bare message including the computed checksum
as a footer annotation, and
* for a receiving link to automatically lookup the expected CRC-32
or Adler-32 checksum in the footer annotation and, if present, check
the received checksum against the actually computed checksum.
The commit comes with the following advantages:
1. Transparent end-to-end checksumming. Although checksumming is
performed by TCP and RabbitMQ queues using the disk, end-to-end
checksumming is a level higher up and can therefore detect bit flips
within RabbitMQ nodes or load balancers and other bit flips that
went unnoticed.
2. Not only is the body checksummed, but also the properties and
application-properties sections. This is an advantage over AMQP 0.9.1
because the AMQP protocol disallows modification of the bare message.
3. This commit is currently used for testing the RabbitMQ AMQP
implementation, but it shows the feasiblity of how apps could also
get integrity guarantees of the whole bare message using HMACs or
signatures.
This commit fixes test
```
bazel test //deps/rabbitmq_mqtt:shared_SUITE-mixed -t- \
--test_sharding_strategy=disabled --test_env \
FOCUS="-group [mqtt,v3,cluster_size_3] -case pubsub"
```
Fix some mixed version tests
Assume the AMQP body, especially amqp-value section won't be parsed.
Hence, omit smart conversions from AMQP to MQTT involving the
Payload-Format-Indicator bit.
Fix test
Fix
```
bazel test //deps/amqp10_client:system_SUITE-mixed -t- --test_sharding_strategy=disabled --test_env FOCUS="-group [rabbitmq]
```
When generating iodata() in the AMQP 1.0 generator, prefer integers over
binaries.
Rename functions and variable names to better reflect the AMQP 1.0 spec
instead of using AMQP 0.9.1 wording.
## What?
Introduce a new address format (let's call it v2) for AMQP 1.0 source and target addresses.
The old format (let's call it v1) is described in
https://github.com/rabbitmq/rabbitmq-server/tree/v3.13.x/deps/rabbitmq_amqp1_0#routing-and-addressing
The only v2 source address format is:
```
/queue/:queue
```
The 4 possible v2 target addresses formats are:
```
/exchange/:exchange/key/:routing-key
/exchange/:exchange
/queue/:queue
<null>
```
where the last AMQP <null> value format requires that each message’s `to` field contains one of:
```
/exchange/:exchange/key/:routing-key
/exchange/:exchange
/queue/:queue
```
## Why?
The AMQP address v1 format comes with the following flaws:
1. Obscure address format:
Without reading the documentation, the differences for example between source addresses
```
/amq/queue/:queue
/queue/:queue
:queue
```
are unknown to users. Hence, the address format is obscure.
2. Implicit creation of topologies
Some address formats implicitly create queues (and bindings), such as source address
```
/exchange/:exchange/:binding-key
```
or target address
```
/queue/:queue
```
These queues and bindings are never deleted (by the AMQP 1.0 plugin.)
Implicit creation of such topologies is also obscure.
3. Redundant address formats
```
/queue/:queue
:queue
```
have the same meaning and are therefore redundant.
4. Properties section must be parsed to determine whether a routing key is present
Target address
```
/exchange/:exchange
```
requires RabbitMQ to parse the properties section in order to check whether the message `subject` is set.
If `subject` is not set, the routing key will default to the empty string.
5. Using `subject` as routing key misuses the purpose of this field.
According to the AMQP spec, the message `subject` field's purpose is:
> A common field for summary information about the message content and purpose.
6. Exchange names, queue names and routing keys must not contain the "/" (slash) character.
The current 3.13 implemenation splits by "/" disallowing these
characters in exchange, and queue names, and routing keys which is
unnecessary prohibitive.
7. Clients must create a separate link per target exchange
While this is reasonable working assumption, there might be rare use
cases where it could make sense to create many exchanges (e.g. 1
exchange per queue, see
https://github.com/rabbitmq/rabbitmq-server/discussions/10708) and have
a single application publish to all these exchanges.
With the v1 address format, for an application to send to 500 different
exchanges, it needs to create 500 links.
Due to these disadvantages and thanks to #10559 which allows clients to explicitly create topologies,
we can create a simpler, clearer, and better v2 address format.
## How?
### Design goals
Following the 7 cons from v1, the design goals for v2 are:
1. The address format should be simple so that users have a chance to
understand the meaning of the address without necessarily consulting the docs.
2. The address format should not implicitly create queues, bindings, or exchanges.
Instead, topologies should be created either explicitly via the new management node
prior to link attachment (see #10559), or in future, we might support the `dynamic`
source or target properties so that RabbitMQ creates queues dynamically.
3. No redundant address formats.
4. The target address format should explicitly state whether the routing key is present, empty,
or will be provided dynamically in each message.
5. `Subject` should not be used as routing key. Instead, a better
fitting field should be used.
6. Exchange names, queue names, and routing keys should allow to contain
valid UTF-8 encoded data including the "/" character.
7. Allow both target exchange and routing key to by dynamically provided within each message.
Furthermore
8. v2 must co-exist with v1 for at least some time. Applications should be able to upgrade to
RabbitMQ 4.0 while continuing to use v1. Examples include AMQP 1.0 shovels and plugins communicating
between a 4.0 and a 3.13 cluster. Starting with 4.1, we should change the AMQP 1.0 shovel and plugin clients
to use only the new v2 address format. This will allow AMQP 1.0 and plugins to communicate between a 4.1 and 4.2 cluster.
We will deprecate v1 in 4.0 and remove support for v1 in a later 4.x version.
### Additional Context
The address is usually a String, but can be of any type.
The [AMQP Addressing extension](https://docs.oasis-open.org/amqp/addressing/v1.0/addressing-v1.0.html)
suggests that addresses are URIs and are therefore hierarchical and could even contain query parameters:
> An AMQP address is a URI reference as defined by RFC3986.
> the path expression is a sequence of identifier segments that reflects a path through an
> implementation specific relationship graph of AMQP nodes and their termini.
> The path expression MUST resolve to a node’s terminus in an AMQP container.
The [Using the AMQP Anonymous Terminus for Message Routing Version 1.0](https://docs.oasis-open.org/amqp/anonterm/v1.0/cs01/anonterm-v1.0-cs01.html)
extension allows for the target being `null` and the `To` property to contain the node address.
This corresponds to AMQP 0.9.1 where clients can send each message on the same channel to a different `{exchange, routing-key}` destination.
The following v2 address formats will be used.
### v2 addresses
A new deprecated feature flag `amqp_address_v1` will be introduced in 4.0 which is permitted by default.
Starting with 4.1, we should change the AMQP 1.0 shovel and plugin AMQP 1.0 clients to use only the new v2 address format.
However, 4.1 server code must still understand the 4.0 AMQP 1.0 shovel and plugin AMQP 1.0 clients’ v1 address format.
The new deprecated feature flag will therefore be denied by default in 4.2.
This allows AMQP 1.0 shovels and plugins to work between
* 4.0 and 3.13 clusters using v1
* 4.1 and 4.0 clusters using v2 from 4.1 to v4.0 and v1 from 4.0 to 4.1
* 4.2 and 4.1 clusters using v2
without having to support both v1 and v2 at the same time in the AMQP 1.0 shovel and plugin clients.
While supporting both v1 and v2 in these clients is feasible, it's simpler to switch the client code directly from v1 to v2.
### v2 source addresses
The source address format is
```
/queue/:queue
```
If the deprecated feature flag `amqp_address_v1` is permitted and the queue does not exist, the queue will be auto-created.
If the deprecated feature flag `amqp_address_v1` is denied, the queue must exist.
### v2 target addresses
v1 requires attaching a new link for each destination exchange.
v2 will allow dynamic `{exchange, routing-key}` combinations for a given link.
v2 therefore allows for the rare use cases where a single AMQP 1.0 publisher app needs to send to many different exchanges.
Setting up a link per destination exchange could be cumbersome.
Hence, v2 will support the dynamic `{exchange, routing-key}` combinations of AMQP 0.9.1.
To achieve this, we make use of the "Anonymous Terminus for Message Routing" extension:
The target address will contain the AMQP value null.
The `To` field in each message must be set and contain either address format
```
/exchange/:exchange/key/:routing-key
```
or
```
/exchange/:exchange
```
when using the empty routing key.
The `to` field requires an address type and is better suited than the `subject field.
Note that each message will contain this `To` value for the anonymous terminus.
Hence, we should save some bytes being sent across the network and stored on disk.
Using a format
```
/e/:exchange/k/:routing-key
```
saves more bytes, but is too obscure.
However, we use only `/key/` instead of `/routing-key/` so save a few bytes.
This also simplifies the format because users don’t have to remember whether to use spell `routing-key` or `routing_key` or `routingkey`.
The other allowed target address formats are:
```
/exchange/:exchange/key/:routing-key
```
where exchange and routing key are static on the given link.
```
/exchange/:exchange
```
where exchange and routing key are static on the given link, and routing key will be the empty string (useful for example for the fanout exchange).
```
/queue/:queue
```
This provides RabbitMQ beginners the illusion of sending a message directly
to a queue without having to understand what exchanges and routing keys are.
If the deprecated feature flag `amqp_address_v1` is permitted and the queue does not exist, the queue will be auto-created.
If the deprecated feature flag `amqp_address_v1` is denied, the queue must exist.
Besides the additional queue existence check, this queue target is different from
```
/exchange//key/:queue
```
in that queue specific optimisations might be done (in future) by RabbitMQ
(for example different receiving queue types could grant different amounts of link credits to the sending clients).
A write permission check to the amq.default exchange will be performed nevertheless.
v2 will prohibit the v1 static link & dynamic routing-key combination
where the routing key is sent in the message `subject` as that’s also obscure.
For this use case, v2’s new anonymous terminus can be used where both exchange and routing key are defined in the message’s `To` field.
(The bare message must not be modified because it could be signed.)
The alias format
```
/topic/:topic
```
will also be removed.
Sending to topic exchanges is arguably an advanced feature.
Users can directly use the format
```
/exchange/amq.topic/key/:topic
```
which reduces the number of redundant address formats.
### v2 address format reference
To sump up (and as stated at the top of this commit message):
The only v2 source address format is:
```
/queue/:queue
```
The 4 possible v2 target addresses formats are:
```
/exchange/:exchange/key/:routing-key
/exchange/:exchange
/queue/:queue
<null>
```
where the last AMQP <null> value format requires that each message’s `to` field contains one of:
```
/exchange/:exchange/key/:routing-key
/exchange/:exchange
/queue/:queue
```
Hence, all 8 listed design goals are reached.
## What?
* Allow AMQP 1.0 clients to dynamically create and delete RabbitMQ
topologies (exchanges, queues, bindings).
* Provide an Erlang AMQP 1.0 client that manages topologies.
## Why?
Today, RabbitMQ topologies can be created via:
* [Management HTTP API](https://www.rabbitmq.com/docs/management#http-api)
(including Management UI and
[messaging-topology-operator](https://github.com/rabbitmq/messaging-topology-operator))
* [Definition Import](https://www.rabbitmq.com/docs/definitions#import)
* AMQP 0.9.1 clients
Up to RabbitMQ 3.13 the RabbitMQ AMQP 1.0 plugin auto creates queues
and bindings depending on the terminus [address
format](https://github.com/rabbitmq/rabbitmq-server/tree/v3.13.x/deps/rabbitmq_amqp1_0#routing-and-addressing).
Such implicit creation of topologies is limiting and obscure.
For some address formats, queues will be created, but not deleted.
Some of RabbitMQ's success is due to its flexible routing topologies
that AMQP 0.9.1 clients can create and delete dynamically.
This commit allows dynamic management of topologies for AMQP 1.0 clients.
This commit builds on top of Native AMQP 1.0 (PR #9022) and will be
available in RabbitMQ 4.0.
## How?
This commits adds the following management operations for AMQP 1.0 clients:
* declare queue
* delete queue
* purge queue
* bind queue to exchange
* unbind queue from exchange
* declare exchange
* delete exchange
* bind exchange to exchange
* unbind exchange from exchange
Hence, at least the AMQP 0.9.1 management operations are supported for
AMQP 1.0 clients.
In addition the operation
* get queue
is provided which - similar to `declare queue` - returns queue
information including the current leader and replicas.
This allows clients to publish or consume locally on the node that hosts
the queue.
Compared to AMQP 0.9.1 whose commands and command fields are fixed, the
new AMQP Management API is extensible: New operations and new fields can
easily be added in the future.
There are different design options how management operations could be
supported for AMQP 1.0 clients:
1. Use a special exchange type as done in https://github.com/rabbitmq/rabbitmq-management-exchange
This has the advantage that any protocol client (e.g. also STOMP clients) could
dynamically manage topologies. However, a special exchange type is the wrong abstraction.
2. Clients could send "special" messages with special headers that the broker interprets.
This commit decided for a variation of the 2nd option using a more
standardized way by re-using a subest of the following latest AMQP 1.0 extension
specifications:
* [AMQP Request-Response Messaging with Link Pairing Version 1.0 - Committee Specification 01](https://docs.oasis-open.org/amqp/linkpair/v1.0/cs01/linkpair-v1.0-cs01.html) (February 2021)
* [HTTP Semantics and Content over AMQP Version 1.0 - Working Draft 06](https://groups.oasis-open.org/higherlogic/ws/public/document?document_id=65571) (July 2019)
* [AMQP Management Version 1.0 - Working Draft 16](https://groups.oasis-open.org/higherlogic/ws/public/document?document_id=65575) (July 2019)
An important goal is to keep the interaction between AMQP 1.0 client and RabbitMQ
simple to increase usage, development and adoptability of future RabbitMQ AMQP 1.0
client library wrappers.
The AMQP 1.0 client has to create a link pair to the special `/management` node.
This allows the client to send and receive from the management node.
Similar to AMQP 0.9.1, there is no need for a reply queue since the reply
will be sent directly to the client.
Requests and responses are modelled via HTTP, but sent via AMQP using
the `HTTP Semantics and Content over AMQP` extension (henceforth `HTTP
over AMQP` extension).
This commit tries to follow the `HTTP over AMQP` extension as much as
possible but deviates where this draft spec doesn't make sense.
The projected mode §4.1 is used as opposed to tunneled mode §4.2.
A named relay `/management` is used (§6.3) where the message field `to` is the URL.
Deviations are
* §3.1 mandates that URIs are not encoded in an AMQP message.
However, we percent encode URIs in the AMQP message. Otherwise there
is for example no way to distinguish a `/` in a queue name from the
URI path separator `/`.
* §4.1.4 mandates a data section. This commit uses an amqp-value section
as it's a better fit given that the content is AMQP encoded data.
Using an HTTP API allows for a common well understood interface and future extensibility.
Instead of re-using the current RabbitMQ HTTP API, this commit uses a
new HTTP API (let's call it v2) which could be used as a future API for
plain HTTP clients.
### HTTP API v1
The current HTTP API (let's call it v1) is **not** used since v1
comes with a couple of weaknesses:
1. Deep level of nesting becomes confusing and difficult to manage.
Examples of deep nesting in v1:
```
/api/bindings/vhost/e/source/e/destination/props
/api/bindings/vhost/e/exchange/q/queue/props
```
2. Redundant endpoints returning the same resources
v1 has 9 endpoints to list binding(s):
```
/api/exchanges/vhost/name/bindings/source
/api/exchanges/vhost/name/bindings/destination
/api/queues/vhost/name/bindings
/api/bindings
/api/bindings/vhost
/api/bindings/vhost/e/exchange/q/queue
/api/bindings/vhost/e/exchange/q/queue/props
/api/bindings/vhost/e/source/e/destination
/api/bindings/vhost/e/source/e/destination/props
```
3. Verbs in path names
Path names should be nouns instead.
v1 contains verbs:
```
/api/queues/vhost/name/get
/api/exchanges/vhost/name/publish
```
### AMQP Management extension
Only few aspects of the AMQP Management extension are used.
The central idea of the AMQP management spec is **dynamic discovery** such that broker independent AMQP 1.0
clients can discover objects, types, operations, and HTTP endpoints of specific brokers.
In fact, clients are only conformant if:
> All request addresses are dynamically discovered starting from the discovery document.
> A requesting container MUST NOT use fixed assumptions about the addressing structure of the management API.
While this is a nice and powerful idea, no AMQP 1.0 client and no AMQP 1.0 server implement the
latest AMQP 1.0 management spec from 2019, partly presumably due to its complexity.
Therefore, the idea of such dynamic discovery has failed to be implemented in practice.
The AMQP management spec mandates that the management endpoint returns a discovery document containing
broker specific collections, types, configuration, and operations including their endpoints.
The API endpoints of the AMQP management spec are therefore all designed around dynamic discovery.
For example, to create either a queue or an exchange, the client has to
```
POST /$management/entities
```
which shows that the entities collection acts as a generic factory, see section 2.2.
The server will then create the resource and reply with a location header containing a URI pointing to the resource.
For RabbitMQ, we don’t need such a generic factory to create queues or exchanges.
To list bindings for a queue Q1, the spec suggests
```
GET /$management/Queues/Q1/$management/entities
```
which again shows the generic entities endpoint as well as a `$management` endpoint under Q1 to
allow a queue to return a discovery document.
For RabbitMQ, we don’t need such generic endpoints and discovery documents.
Given we aim for our own thin RabbitMQ AMQP 1.0 client wrapper libraries which expose
the RabbitMQ model to the developer, we can directly use fixed HTTP endpoint assumptions
in our RabbitMQ specific libraries.
This is by far simpler than using the dynamic endpoints of the management spec.
Simplicity leads to higher adoption and enables more developers to write RabbitMQ AMQP 1.0 client
library wrappers.
The AMQP Management extension also suffers from deep level of nesting in paths
Examples:
```
/$management/Queues/Q1/$management/entities
/$management/Queues/Q1/Bindings/Binding1
```
as well as verbs in path names: Section 7.1.4 suggests using verbs in path names,
for example “purge”, due to the dynamic operations discovery document.
### HTTP API v2
This commit introduces a new HTTP API v2 following best practices.
It could serve as a future API for plain HTTP clients.
This commit and RabbitMQ 4.0 will only implement a minimal set of
HTTP API v2 endpoints and only for HTTP over AMQP.
In other words, the existing HTTP API v1 Cowboy handlers will continue to be
used for all plain HTTP requests in RabbitMQ 4.0 and will remain untouched for RabbitMQ 4.0.
Over time, after 4.0 shipped, we could ship a pure HTTP API implementation for HTTP API v2.
Hence, the new HTTP API v2 endpoints for HTTP over AMQP should be designed such that they
can be re-used in the future for a pure HTTP implementation.
The minimal set of endpoints for RabbitMQ 4.0 are:
``
GET / PUT / DELETE
/vhosts/:vhost/queues/:queue
```
read, create, delete a queue
```
DELETE
/vhosts/:vhost/queues/:queue/messages
```
purges a queue
```
GET / DELETE
/vhosts/:vhost/bindings/:binding
```
read, delete bindings
where `:binding` is a binding ID of the following path segment:
```
src=e1;dstq=q2;key=my-key;args=
```
Binding arguments `args` has an empty value by default, i.e. there are no binding arguments.
If the binding includes binding arguments, `args` will be an Erlang portable term hash
provided by the server similar to what’s provided in HTTP API v1 today.
Alternatively, we could use an arguments scheme of:
```
args=k1,utf8,v1&k2,uint,3
```
However, such a scheme leads to long URIs when there are many binding arguments.
Note that it’s perfectly fine for URI producing applications to include URI
reserved characters `=` / `;` / `,` / `$` in a path segment.
To create a binding, the client therefore needs to POST to a bindings factory URI:
```
POST
/vhosts/:vhost/bindings
```
To list all bindings between a source exchange e1 and destination exchange e2 with binding key k1:
```
GET
/vhosts/:vhost/bindings?src=e1&dste=e2&key=k1
```
This endpoint will be called by the RabbitMQ AMQP 1.0 client library to unbind a
binding with non-empty binding arguments to get the binding ID before invoking a
```
DELETE
/vhosts/:vhost/bindings/:binding
```
In future, after RabbitMQ 4.0 shipped, new API endpoints could be added.
The following is up for discussion and is only meant to show the clean and simple design of HTTP API v2.
Bindings endpoint can be queried as follows:
to list all bindings for a given source exchange e1:
```
GET
/vhosts/:vhost/bindings?src=e1
```
to list all bindings for a given destination queue q1:
```
GET
/vhosts/:vhost/bindings?dstq=q1
```
to list all bindings between a source exchange e1 and destination queue q1:
```
GET
/vhosts/:vhost/bindings?src=e1&dstq=q1
```
multiple bindings between source exchange e1 and destination queue q1 could be deleted at once as follows:
```
DELETE /vhosts/:vhost/bindings?src=e1&dstq=q1
```
GET could be supported globally across all vhosts:
```
/exchanges
/queues
/bindings
```
Publish a message:
```
POST
/vhosts/:vhost/queues/:queue/messages
```
Consume or peek a message (depending on query parameters):
```
GET
/vhosts/:vhost/queues/:queue/messages
```
Note that the AMQP 1.0 client omits the `/vhost/:vhost` path prefix.
Since an AMQP connection belongs to a single vhost, there is no need to
additionally include the vhost in every HTTP request.
Pros of HTTP API v2:
1. Low level of nesting
Queues, exchanges, bindings are top level entities directly under vhosts.
Although the HTTP API doesn’t have to reflect how resources are stored in the database,
v2 does nicely reflect the Khepri tree structure.
2. Nouns instead of verbs
HTTP API v2 is very simple to read and understand as shown by
```
POST /vhosts/:vhost/queues/:queue/messages to post messages, i.e. publish to a queue.
GET /vhosts/:vhost/queues/:queue/messages to get messages, i.e. consume or peek from a queue.
DELETE /vhosts/:vhost/queues/:queue/messages to delete messages, i.e. purge a queue.
```
A separate new HTTP API v2 allows us to ship only handlers for HTTP over AMQP for RabbitMQ 4.0
and therefore move faster while still keeping the option on the table to re-use the new v2 API
for pure HTTP in the future.
In contrast, re-using the HTTP API v1 for HTTP over AMQP is possible, but dirty because separate handlers
(HTTP over AMQP and pure HTTP) replying differently will be needed for the same v1 endpoints.
What?
Protect receiving application from being overloaded with new messages
while still processing existing messages if the auto credit renewal
feature of the Erlang AMQP 1.0 client library is used.
This feature can therefore be thought of as a prefetch window equivalent
in AMQP 0.9.1 or MQTT 5.0 property Receive Maximum.
How?
The credit auto renewal feature in RabbitMQ 3.x was wrongly implemented.
This commit takes the same approach as done in the server:
The incoming_unsettled map is hold in the link instead of in the session
to accurately and quickly determine the number of unsettled messages for
a receiving link.
The amqp10_client lib will grant more credits to the sender when the sum
of remaining link credits and number of unsettled deliveries falls below
the threshold RenewWhenBelow.
This avoids maintaning additional state like the `link_credit_unsettled`
or an alternative delivery_count_settled sequence number which is more
complex to implement correctly.
This commit breaks the amqp10_client_session:disposition/6 API:
This commit forces the client application to only range settle for a
given link, i.e. not across multiple links on a given session at once.
The latter is allowed according to the AMQP spec.
## What
Similar to Native MQTT in #5895, this commits implements Native AMQP 1.0.
By "native", we mean do not proxy via AMQP 0.9.1 anymore.
## Why
Native AMQP 1.0 comes with the following major benefits:
1. Similar to Native MQTT, this commit provides better throughput, latency,
scalability, and resource usage for AMQP 1.0.
See https://blog.rabbitmq.com/posts/2023/03/native-mqtt for native MQTT improvements.
See further below for some benchmarks.
2. Since AMQP 1.0 is not limited anymore by the AMQP 0.9.1 protocol,
this commit allows implementing more AMQP 1.0 features in the future.
Some features are already implemented in this commit (see next section).
3. Simpler, better understandable, and more maintainable code.
Native AMQP 1.0 as implemented in this commit has the
following major benefits compared to AMQP 0.9.1:
4. Memory and disk alarms will only stop accepting incoming TRANSFER frames.
New connections can still be created to consume from RabbitMQ to empty queues.
5. Due to 4. no need anymore for separate connections for publishers and
consumers as we currently recommended for AMQP 0.9.1. which potentially
halves the number of physical TCP connections.
6. When a single connection sends to multiple target queues, a single
slow target queue won't block the entire connection.
Publisher can still send data quickly to all other target queues.
7. A publisher can request whether it wants publisher confirmation on a per-message basis.
In AMQP 0.9.1 publisher confirms are configured per channel only.
8. Consumers can change their "prefetch count" dynamically which isn't
possible in our AMQP 0.9.1 implementation. See #10174
9. AMQP 1.0 is an extensible protocol
This commit also fixes dozens of bugs present in the AMQP 1.0 plugin in
RabbitMQ 3.x - most of which cannot be backported due to the complexity
and limitations of the old 3.x implementation.
This commit contains breaking changes and is therefore targeted for RabbitMQ 4.0.
## Implementation details
1. Breaking change: With Native AMQP, the behaviour of
```
Convert AMQP 0.9.1 message headers to application properties for an AMQP 1.0 consumer
amqp1_0.convert_amqp091_headers_to_app_props = false | true (default false)
Convert AMQP 1.0 Application Properties to AMQP 0.9.1 headers
amqp1_0.convert_app_props_to_amqp091_headers = false | true (default false)
```
will break because we always convert according to the message container conversions.
For example, AMQP 0.9.1 x-headers will go into message-annotations instead of application properties.
Also, `false` won’t be respected since we always convert the headers with message containers.
2. Remove rabbit_queue_collector
rabbit_queue_collector is responsible for synchronously deleting
exclusive queues. Since the AMQP 1.0 plugin never creates exclusive
queues, rabbit_queue_collector doesn't need to be started in the first
place. This will save 1 Erlang process per AMQP 1.0 connection.
3. 7 processes per connection + 1 process per session in this commit instead of
7 processes per connection + 15 processes per session in 3.x
Supervision hierarchy got re-designed.
4. Use 1 writer process per AMQP 1.0 connection
AMQP 0.9.1 uses a separate rabbit_writer Erlang process per AMQP 0.9.1 channel.
Prior to this commit, AMQP 1.0 used a separate rabbit_amqp1_0_writer process per AMQP 1.0 session.
Advantage of single writer proc per session (prior to this commit):
* High parallelism for serialising packets if multiple sessions within
a connection write heavily at the same time.
This commit uses a single writer process per AMQP 1.0 connection that is
shared across all AMQP 1.0 sessions.
Advantages of single writer proc per connection (this commit):
* Lower memory usage with hundreds of thousands of AMQP 1.0 sessions
* Less TCP and IP header overhead given that the single writer process
can accumulate across all sessions bytes before flushing the socket.
In other words, this commit decides that a reader / writer process pair
per AMQP 1.0 connection is good enough for bi-directional TRANSFER flows.
Having a writer per session is too heavy.
We still ensure high throughput by having separate reader, writer, and
session processes.
5. Transform rabbit_amqp1_0_writer into gen_server
Why:
Prior to this commit, when clicking on the AMQP 1.0 writer process in
observer, the process crashed.
Instead of handling all these debug messages of the sys module, it's better
to implement a gen_server.
There is no advantage of using a special OTP process over gen_server
for the AMQP 1.0 writer.
gen_server also provides cleaner format status output.
How:
Message callbacks return a timeout of 0.
After all messages in the inbox are processed, the timeout message is
handled by flushing any pending bytes.
6. Remove stats timer from writer
AMQP 1.0 connections haven't emitted any stats previously.
7. When there are contiguous queue confirmations in the session process
mailbox, batch them. When the confirmations are sent to the publisher, a
single DISPOSITION frame is sent for contiguously confirmed delivery
IDs.
This approach should be good enough. However it's sub optimal in
scenarios where contiguous delivery IDs that need confirmations are rare,
for example:
* There are multiple links in the session with different sender
settlement modes and sender publishes across these links interleaved.
* sender settlement mode is mixed and sender publishes interleaved settled
and unsettled TRANSFERs.
8. Introduce credit API v2
Why:
The AMQP 0.9.1 credit extension which is to be removed in 4.0 was poorly
designed since basic.credit is a synchronous call into the queue process
blocking the entire AMQP 1.0 session process.
How:
Change the interactions between queue clients and queue server
implementations:
* Clients only request a credit reply if the FLOW's `echo` field is set
* Include all link flow control state held by the queue process into a
new credit_reply queue event:
* `available` after the queue sends any deliveries
* `link-credit` after the queue sends any deliveries
* `drain` which allows us to combine the old queue events
send_credit_reply and send_drained into a single new queue event
credit_reply.
* Include the consumer tag into the credit_reply queue event such that
the AMQP 1.0 session process can process any credit replies
asynchronously.
Link flow control state `delivery-count` also moves to the queue processes.
The new interactions are hidden behind feature flag credit_api_v2 to
allow for rolling upgrades from 3.13 to 4.0.
9. Use serial number arithmetic in quorum queues and session process.
10. Completely bypass the rabbit_limiter module for AMQP 1.0
flow control. The goal is to eventually remove the rabbit_limiter module
in 4.0 since AMQP 0.9.1 global QoS will be unsupported in 4.0. This
commit lifts the AMQP 1.0 link flow control logic out of rabbit_limiter
into rabbit_queue_consumers.
11. Fix credit bug for streams:
AMQP 1.0 settlements shouldn't top up link credit,
only FLOW frames should top up link credit.
12. Allow sender settle mode unsettled for streams
since AMQP 1.0 acknowledgements to streams are no-ops (currently).
13. Fix AMQP 1.0 client bugs
Auto renewing credits should not be related to settling TRANSFERs.
Remove field link_credit_unsettled as it was wrong and confusing.
Prior to this commit auto renewal did not work when the sender uses
sender settlement mode settled.
14. Fix AMQP 1.0 client bugs
The wrong outdated Link was passed to function auto_flow/2
15. Use osiris chunk iterator
Only hold messages of uncompressed sub batches in memory if consumer
doesn't have sufficient credits.
Compressed sub batches are skipped for non Stream protocol consumers.
16. Fix incoming link flow control
Always use confirms between AMQP 1.0 queue clients and queue servers.
As already done internally by rabbit_fifo_client and
rabbit_stream_queue, use confirms for classic queues as well.
17. Include link handle into correlation when publishing messages to target queues
such that session process can correlate confirms from target queues to
incoming links.
18. Only grant more credits to publishers if publisher hasn't sufficient credits
anymore and there are not too many unconfirmed messages on the link.
19. Completely ignore `block` and `unblock` queue actions and RabbitMQ credit flow
between classic queue process and session process.
20. Link flow control is independent between links.
A client can refer to a queue or to an exchange with multiple
dynamically added target queues. Multiple incoming links can also fan
in to the same queue. However the link topology looks like, this
commit ensures that each link is only granted more credits if that link
isn't overloaded.
21. A connection or a session can send to many different queues.
In AMQP 0.9.1, a single slow queue will lead to the entire channel, and
then entire connection being blocked.
This commit makes sure that a single slow queue from one link won't slow
down sending on other links.
For example, having link A sending to a local classic queue and
link B sending to 5 replica quorum queue, link B will naturally
grant credits slower than link A. So, despite the quorum queue being
slower in confirming messages, the same AMQP 1.0 connection and session
can still pump data very fast into the classic queue.
22. If cluster wide memory or disk alarm occurs.
Each session sends a FLOW with incoming-window to 0 to sending client.
If sending clients don’t obey, force disconnect the client.
If cluster wide memory alarm clears:
Each session resumes with a FLOW defaulting to initial incoming-window.
23. All operations apart of publishing TRANSFERS to RabbitMQ can continue during cluster wide alarms,
specifically, attaching consumers and consuming, i.e. emptying queues.
There is no need for separate AMQP 1.0 connections for publishers and consumers as recommended in our AMQP 0.9.1 implementation.
24. Flow control summary:
* If queue becomes bottleneck, that’s solved by slowing down individual sending links (AMQP 1.0 link flow control).
* If session becomes bottleneck (more unlikely), that’s solved by AMQP 1.0 session flow control.
* If connection becomes bottleneck, it naturally won’t read fast enough from the socket causing TCP backpressure being applied.
Nowhere will RabbitMQ internal credit based flow control (i.e. module credit_flow) be used on the incoming AMQP 1.0 message path.
25. Register AMQP sessions
Prefer local-only pg over our custom pg_local implementation as
pg is a better process group implementation than pg_local.
pg_local was identified as bottleneck in tests where many MQTT clients were disconnected at once.
26. Start a local-only pg when Rabbit boots:
> A scope can be kept local-only by using a scope name that is unique cluster-wide, e.g. the node name:
> pg:start_link(node()).
Register AMQP 1.0 connections and sessions with pg.
In future we should remove pg_local and instead use the new local-only
pg for all registered processes such as AMQP 0.9.1 connections and channels.
27. Requeue messages if link detached
Although the spec allows to settle delivery IDs on detached links, RabbitMQ does not respect the 'closed'
field of the DETACH frame and therefore handles every DETACH frame as closed. Since the link is closed,
we expect every outstanding delivery to be requeued.
In addition to consumer cancellation, detaching a link therefore causes in flight deliveries to be requeued.
Note that this behaviour is different from merely consumer cancellation in AMQP 0.9.1:
"After a consumer is cancelled there will be no future deliveries dispatched to it. Note that there can
still be "in flight" deliveries dispatched previously. Cancelling a consumer will neither discard nor requeue them."
[https://www.rabbitmq.com/consumers.html#unsubscribing]
An AMQP receiver can first drain, and then detach to prevent "in flight" deliveries
28. Init AMQP session with BEGIN frame
Similar to how there can't be an MQTT processor without a CONNECT
frame, there can't be an AMQP session without a BEGIN frame.
This allows having strict dialyzer types for session flow control
fields (i.e. not allowing 'undefined').
29. Move serial_number to AMQP 1.0 common lib
such that it can be used by both AMQP 1.0 server and client
30. Fix AMQP client to do serial number arithmetic.
31. AMQP client: Differentiate between delivery-id and transfer-id for better
understandability.
32. Fix link flow control in classic queues
This commit fixes
```
java -jar target/perf-test.jar -ad false -f persistent -u cq -c 3000 -C 1000000 -y 0
```
followed by
```
./omq -x 0 amqp -T /queue/cq -D 1000000 --amqp-consumer-credits 2
```
Prior to this commit, (and on RabbitMQ 3.x) the consuming would halt after around
8 - 10,000 messages.
The bug was that in flight messages from classic queue process to
session process were not taken into account when topping up credit to
the classic queue process.
Fixes#2597
The solution to this bug (and a much cleaner design anyway independent of
this bug) is that queues should hold all link flow control state including
the delivery-count.
Hence, when credit API v2 is used the delivery-count will be held by the
classic queue process, quorum queue process, and stream queue client
instead of managing the delivery-count in the session.
33. The double level crediting between (a) session process and
rabbit_fifo_client, and (b) rabbit_fifo_client and rabbit_fifo was
removed. Therefore, instead of managing 3 separate delivery-counts (i. session,
ii. rabbit_fifo_client, iii. rabbit_fifo), only 1 delivery-count is used
in rabbit_fifo. This is a big simplification.
34. This commit fixes quorum queues without bumping the machine version
nor introducing new rabbit_fifo commands.
Whether credit API v2 is used is solely determined at link attachment time
depending on whether feature flag credit_api_v2 is enabled.
Even when that feature flag will be enabled later on, this link will
keep using credit API v1 until detached (or the node is shut down).
Eventually, after feature flag credit_api_v2 has been enabled and a
subsequent rolling upgrade, all links will use credit API v2.
This approach is safe and simple.
The 2 alternatives to move delivery-count from the session process to the
queue processes would have been:
i. Explicit feature flag credit_api_v2 migration function
* Can use a gen_server:call and only finish migration once all delivery-counts were migrated.
Cons:
* Extra new message format just for migration is required.
* Risky as migration will fail if a target queue doesn’t reply.
ii. Session always includes DeliveryCountSnd when crediting to the queue:
Cons:
* 2 delivery counts will be hold simultaneously in session proc and queue proc;
could be solved by deleting the session proc’s delivery-count for credit-reply
* What happens if the receiver doesn’t provide credit for a very long time? Is that a problem?
35. Support stream filtering in AMQP 1.0 (by @acogoluegnes)
Use the x-stream-filter-value message annotation
to carry the filter value in a published message.
Use the rabbitmq:stream-filter and rabbitmq:stream-match-unfiltered
filters when creating a receiver that wants to filter
out messages from a stream.
36. Remove credit extension from AMQP 0.9.1 client
37. Support maintenance mode closing AMQP 1.0 connections.
38. Remove AMQP 0.9.1 client dependency from AMQP 1.0 implementation.
39. Move AMQP 1.0 plugin to the core. AMQP 1.0 is enabled by default.
The old rabbitmq_amqp1_0 plugin will be kept as a no-op plugin to prevent deployment
tools from failing that execute:
```
rabbitmq-plugins enable rabbitmq_amqp1_0
rabbitmq-plugins disable rabbitmq_amqp1_0
```
40. Breaking change: Remove CLI command `rabbitmqctl list_amqp10_connections`.
Instead, list both AMQP 0.9.1 and AMQP 1.0 connections in `list_connections`:
```
rabbitmqctl list_connections protocol
Listing connections ...
protocol
{1, 0}
{0,9,1}
```
## Benchmarks
### Throughput & Latency
Setup:
* Single node Ubuntu 22.04
* Erlang 26.1.1
Start RabbitMQ:
```
make run-broker PLUGINS="rabbitmq_management rabbitmq_amqp1_0" FULL=1 RABBITMQ_SERVER_ADDITIONAL_ERL_ARGS="+S 3"
```
Predeclare durable classic queue cq1, durable quorum queue qq1, durable stream queue sq1.
Start client:
https://github.com/ssorj/quiverhttps://hub.docker.com/r/ssorj/quiver/tags (digest 453a2aceda64)
```
docker run -it --rm --add-host host.docker.internal:host-gateway ssorj/quiver:latest
bash-5.1# quiver --version
quiver 0.4.0-SNAPSHOT
```
1. Classic queue
```
quiver //host.docker.internal//amq/queue/cq1 --durable --count 1m --duration 10m --body-size 12 --credit 1000
```
This commit:
```
Count ............................................. 1,000,000 messages
Duration ............................................... 73.8 seconds
Sender rate .......................................... 13,548 messages/s
Receiver rate ........................................ 13,547 messages/s
End-to-end rate ...................................... 13,547 messages/s
Latencies by percentile:
0% ........ 0 ms 90.00% ........ 9 ms
25% ........ 2 ms 99.00% ....... 14 ms
50% ........ 4 ms 99.90% ....... 17 ms
100% ....... 26 ms 99.99% ....... 24 ms
```
RabbitMQ 3.x (main branch as of 30 January 2024):
```
---------------------- Sender ----------------------- --------------------- Receiver ---------------------- --------
Time [s] Count [m] Rate [m/s] CPU [%] RSS [M] Time [s] Count [m] Rate [m/s] CPU [%] RSS [M] Lat [ms]
----------------------------------------------------- ----------------------------------------------------- --------
2.1 130,814 65,342 6 73.6 2.1 3,217 1,607 0 8.0 511
4.1 163,580 16,367 2 74.1 4.1 3,217 0 0 8.0 0
6.1 229,114 32,767 3 74.1 6.1 3,217 0 0 8.0 0
8.1 261,880 16,367 2 74.1 8.1 67,874 32,296 8 8.2 7,662
10.1 294,646 16,367 2 74.1 10.1 67,874 0 0 8.2 0
12.1 360,180 32,734 3 74.1 12.1 67,874 0 0 8.2 0
14.1 392,946 16,367 3 74.1 14.1 68,604 365 0 8.2 12,147
16.1 458,480 32,734 3 74.1 16.1 68,604 0 0 8.2 0
18.1 491,246 16,367 2 74.1 18.1 68,604 0 0 8.2 0
20.1 556,780 32,767 4 74.1 20.1 68,604 0 0 8.2 0
22.1 589,546 16,375 2 74.1 22.1 68,604 0 0 8.2 0
receiver timed out
24.1 622,312 16,367 2 74.1 24.1 68,604 0 0 8.2 0
quiver: error: PlanoProcessError: Command 'quiver-arrow receive //host.docker.internal//amq/queue/cq1 --impl qpid-proton-c --duration 10m --count 1m --rate 0 --body-size 12 --credit 1000 --transaction-size 0 --timeout 10 --durable --output /tmp/quiver-otujr23y' returned non-zero exit status 1.
Traceback (most recent call last):
File "/usr/local/lib/quiver/python/quiver/pair.py", line 144, in run
_plano.wait(receiver, check=True)
File "/usr/local/lib/quiver/python/plano/main.py", line 1243, in wait
raise PlanoProcessError(proc)
plano.main.PlanoProcessError: Command 'quiver-arrow receive //host.docker.internal//amq/queue/cq1 --impl qpid-proton-c --duration 10m --count 1m --rate 0 --body-size 12 --credit 1000 --transaction-size 0 --timeout 10 --durable --output /tmp/quiver-otujr23y' returned non-zero exit status 1.
```
2. Quorum queue:
```
quiver //host.docker.internal//amq/queue/qq1 --durable --count 1m --duration 10m --body-size 12 --credit 1000
```
This commit:
```
Count ............................................. 1,000,000 messages
Duration .............................................. 101.4 seconds
Sender rate ........................................... 9,867 messages/s
Receiver rate ......................................... 9,868 messages/s
End-to-end rate ....................................... 9,865 messages/s
Latencies by percentile:
0% ....... 11 ms 90.00% ....... 23 ms
25% ....... 15 ms 99.00% ....... 28 ms
50% ....... 18 ms 99.90% ....... 33 ms
100% ....... 49 ms 99.99% ....... 47 ms
```
RabbitMQ 3.x:
```
---------------------- Sender ----------------------- --------------------- Receiver ---------------------- --------
Time [s] Count [m] Rate [m/s] CPU [%] RSS [M] Time [s] Count [m] Rate [m/s] CPU [%] RSS [M] Lat [ms]
----------------------------------------------------- ----------------------------------------------------- --------
2.1 130,814 65,342 9 69.9 2.1 18,430 9,206 5 7.6 1,221
4.1 163,580 16,375 5 70.2 4.1 18,867 218 0 7.6 2,168
6.1 229,114 32,767 6 70.2 6.1 18,867 0 0 7.6 0
8.1 294,648 32,734 7 70.2 8.1 18,867 0 0 7.6 0
10.1 360,182 32,734 6 70.2 10.1 18,867 0 0 7.6 0
12.1 425,716 32,767 6 70.2 12.1 18,867 0 0 7.6 0
receiver timed out
14.1 458,482 16,367 5 70.2 14.1 18,867 0 0 7.6 0
quiver: error: PlanoProcessError: Command 'quiver-arrow receive //host.docker.internal//amq/queue/qq1 --impl qpid-proton-c --duration 10m --count 1m --rate 0 --body-size 12 --credit 1000 --transaction-size 0 --timeout 10 --durable --output /tmp/quiver-b1gcup43' returned non-zero exit status 1.
Traceback (most recent call last):
File "/usr/local/lib/quiver/python/quiver/pair.py", line 144, in run
_plano.wait(receiver, check=True)
File "/usr/local/lib/quiver/python/plano/main.py", line 1243, in wait
raise PlanoProcessError(proc)
plano.main.PlanoProcessError: Command 'quiver-arrow receive //host.docker.internal//amq/queue/qq1 --impl qpid-proton-c --duration 10m --count 1m --rate 0 --body-size 12 --credit 1000 --transaction-size 0 --timeout 10 --durable --output /tmp/quiver-b1gcup43' returned non-zero exit status 1.
```
3. Stream:
```
quiver-arrow send //host.docker.internal//amq/queue/sq1 --durable --count 1m -d 10m --summary --verbose
```
This commit:
```
Count ............................................. 1,000,000 messages
Duration ................................................ 8.7 seconds
Message rate ........................................ 115,154 messages/s
```
RabbitMQ 3.x:
```
Count ............................................. 1,000,000 messages
Duration ............................................... 21.2 seconds
Message rate ......................................... 47,232 messages/s
```
### Memory usage
Start RabbitMQ:
```
ERL_MAX_PORTS=3000000 RABBITMQ_SERVER_ADDITIONAL_ERL_ARGS="+P 3000000 +S 6" make run-broker PLUGINS="rabbitmq_amqp1_0" FULL=1 RABBITMQ_CONFIG_FILE="rabbitmq.conf"
```
```
/bin/cat rabbitmq.conf
tcp_listen_options.sndbuf = 2048
tcp_listen_options.recbuf = 2048
vm_memory_high_watermark.relative = 0.95
vm_memory_high_watermark_paging_ratio = 0.95
loopback_users = none
```
Create 50k connections with 2 sessions per connection, i.e. 100k session in total:
```go
package main
import (
"context"
"log"
"time"
"github.com/Azure/go-amqp"
)
func main() {
for i := 0; i < 50000; i++ {
conn, err := amqp.Dial(context.TODO(), "amqp://nuc", &amqp.ConnOptions{SASLType: amqp.SASLTypeAnonymous()})
if err != nil {
log.Fatal("dialing AMQP server:", err)
}
_, err = conn.NewSession(context.TODO(), nil)
if err != nil {
log.Fatal("creating AMQP session:", err)
}
_, err = conn.NewSession(context.TODO(), nil)
if err != nil {
log.Fatal("creating AMQP session:", err)
}
}
log.Println("opened all connections")
time.Sleep(5 * time.Hour)
}
```
This commit:
```
erlang:memory().
[{total,4586376480},
{processes,4025898504},
{processes_used,4025871040},
{system,560477976},
{atom,1048841},
{atom_used,1042841},
{binary,233228608},
{code,21449982},
{ets,108560464}]
erlang:system_info(process_count).
450289
```
7 procs per connection + 1 proc per session.
(7 + 2*1) * 50,000 = 450,000 procs
RabbitMQ 3.x:
```
erlang:memory().
[{total,15168232704},
{processes,14044779256},
{processes_used,14044755120},
{system,1123453448},
{atom,1057033},
{atom_used,1052587},
{binary,236381264},
{code,21790238},
{ets,391423744}]
erlang:system_info(process_count).
1850309
```
7 procs per connection + 15 per session
(7 + 2*15) * 50,000 = 1,850,000 procs
50k connections + 100k session require
with this commit: 4.5 GB
in RabbitMQ 3.x: 15 GB
## Future work
1. More efficient parser and serializer
2. TODO in mc_amqp: Do not store the parsed message on disk.
3. Implement both AMQP HTTP extension and AMQP management extension to allow AMQP
clients to create RabbitMQ objects (queues, exchanges, ...).
David Ansari
GitHub
Diana Parra Corbacho
Michael Klishin
Lois Soto Lopez
Loïc Hoguin
Karl Nilsson
Michael Klishin
Péter Gömöri
Michal Kuratczyk