This pull request replaces Log4j with Log4j2 across the entire project, including dependencies, configurations, and code. The notable changes are listed below:
1. Introduce Log4j2 Instead of Log4j
2. Change Configuration File Format from Properties to YAML
3. Adds warnings to notify users if they are still using Log4j properties, encouraging them to transition to Log4j2 configurations
Co-authored-by: Lee Dongjin <dongjin@apache.org>
Reviewers: Luke Chen <showuon@gmail.com>, Mickael Maison <mickael.maison@gmail.com>, Chia-Ping Tsai <chia7712@gmail.com>
`Self-managed` is also used in the context of Cloud vs on-prem and it can
be confusing.
`KRaft` is a cute combination of `Kafka Raft` and it's pronounced like `craft`
(as in `craftsmanship`).
Reviewers: Colin P. McCabe <cmccabe@apache.org>, Jose Sancio <jsancio@gmail.com>, Chia-Ping Tsai <chia7712@gmail.com>, Ron Dagostino <rdagostino@confluent.io>
The patch adds `quorum.append.linger.ms` behavior to the raft implementation. This gives users a powerful knob to tune the impact of fsync. When an append is accepted from the state machine, it is held in an accumulator (similar to the producer) until the configured linger time is exceeded. This allows the implementation to amortize fsync overhead at the expense of some write latency.
The patch also improves our methodology for testing performance. Up to now, we have relied on the producer performance test, but it is difficult to simulate expected controller loads because producer performance is limited by other factors such as the number of producer clients and head-of-line blocking. Instead, this patch adds a workload generator which runs on the leader after election.
Finally, this patch brings us nearer to the write semantics expected by the KIP-500 controller. It makes the following changes:
- Introduce `RecordSerde<T>` interface which abstracts the underlying log implementation from `RaftClient`. The generic type is carried over to `RaftClient<T>` and is exposed through the read/write APIs.
- `RaftClient.append` is changed to `RaftClient.scheduleAppend` and returns the last offset of the expected log append.
- `RaftClient.scheduleAppend` accepts a list of records and ensures that the full set are included in a single batch.
- Introduce `RaftClient.Listener` with a single `handleCommit` API which will eventually replace `RaftClient.read` in order to surface committed data to the controller state machine. Currently `handleCommit` is only used for records appended by the leader.
Reviewers: José Armando García Sancio <jsancio@users.noreply.github.com>, Guozhang Wang <wangguoz@gmail.com>
This is the core Raft implementation specified by KIP-595: https://cwiki.apache.org/confluence/display/KAFKA/KIP-595%3A+A+Raft+Protocol+for+the+Metadata+Quorum. We have created a separate "raft" module where most of the logic resides. The new APIs introduced in this patch in order to support Raft election and such are disabled in the server until the integration with the controller is complete. Until then, there is a standalone server which can be used for testing the performance of the Raft implementation. See `raft/README.md` for details.
Reviewers: Guozhang Wang <wangguoz@gmail.com>, Boyang Chen <boyang@confluent.io>
Co-authored-by: Boyang Chen <boyang@confluent.io>
Co-authored-by: Guozhang Wang <wangguoz@gmail.com>
PoAn Yang
TengYao Chi
Ismael Juma
Jason Gustafson