Prior to this commit, the `ConcurrentLruCache` implementation would not
perform well under certain conditions. As long as the cache capacity was
not reached, the cache would avoid maintaining an eviction queue
(reordering entries depending with least/most recently read). When the
cache capacity was reached, the LRU queue was updated for each
read/write operation. This decreased performance significantly under
contention when the capacity was reached.
This commit completely rewrites the internals of `ConcurrentLruCache`.
`ConcurrentLruCache` is now a specialized version of the
`ConcurrentLinkedHashMap` [1]. This change focuses on buferring read and
write operations, only processing them at certain times to avoid
contention.
When a cached entry is read, a read operation is queued and buffered
operations are drained if the buffer reached a fixed limit. When a new
cache entry is added or removed, a write operation is queued and
triggers a drain attempt. When the capacity is outgrown, the cache polls
items from the eviction queue, which maintains elements with the
least recently used ones first. Entries are removed until the capacity
is under control.
The behavior described here and the buffer sizes are optimized with the
number of available processors in mind. Work is localized as much as
possible on a per-thread basis to avoid contention on the eviction queue.
The new implementation has been tested with the JMH benchmark provided
here, comparing the former `COncurrentLruCache`, the new implementation
as well as the `ConcurrentLinkedHashMap` [1].
When testing with a cache reaching capacity, under contention, with a
10% cache miss, we're seeing a 40x improvement compared to the previous
implementation and performance on par with the reference.
See [2] for how to replicate the benchmark.
[1] https://github.com/ben-manes/concurrentlinkedhashmap
[2] https://github.com/spring-projects/spring-framework/wiki/Micro-Benchmarks
Closes gh-26320
Align IllegalStateException with SQLException handling and propagate
the original exception.
See gh-28669
Co-authored-by: Christoph Mies <chr.mi@web.de>
SQLErrorCodeSQLExceptionTranslator kicks in for user-provided sql-error-codes.xml files. It will still pick up Spring's legacy default error code mappings as well but only when triggered by a (potentially empty) user-provided file in the root of the classpath.
Closes gh-28216
Commit 6316a35 introduced a regression for property names starting with
multiple uppercase letters (such as setEMail(...)).
This commit fixes that regression and includes an additional test to
cover this case.
See gh-27929
Closes gh-27941
@hpoettker made me aware of the ModeEnum in H2 that allows the
parameterized test to be simplified, which was the primary impetus for
this commit.
See gh-27870
Brian Clozel
ben-enfuse-io
Stephane Nicoll
Jiayi Li
Sam Brannen
Marc Wrobel
Juergen Hoeller
Johnny Lim
Kevin Schönfeld
lijun695
Marten Deinum