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https://issues.apache.org/jira/browse/ARTEMIS-2945?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Francesco Nigro updated ARTEMIS-2945:
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Summary: Artemis native JNI code code be replaced by Java (was: LibAIO JNI
code could be rewritten in Java)
> Artemis native JNI code code be replaced by Java
> ------------------------------------------------
>
> Key: ARTEMIS-2945
> URL: https://issues.apache.org/jira/browse/ARTEMIS-2945
> Project: ActiveMQ Artemis
> Issue Type: Improvement
> Components: Broker
> Affects Versions: 2.15.0
> Reporter: Francesco Nigro
> Assignee: Francesco Nigro
> Priority: Major
>
> LibAIO JNI code could be rewritten in Java, while keeping the LibaioContext
> and LibaioFile APIs the same.
>
> There are few benefits from this:
> # simplification of C code logic to ease maintain it
> # quicker development process (implement-try-test-debug cycle) for non-C
> programmers, including simpler integration with Java test suites
> # easier monitoring/telemetry integration
>
> As demonstrations/proofs of such benefits I would introduce several changes
> into the Java version:
> # using the libaio async fdatasync feature to allow the LibaioContext duty
> cycle loop to free CPU resources in order to handle compaction reads without
> being slowed down by an in-progress fdatasync
> # use a lock-free high performance data structure to reuse iocbs instead of
> a locked (using a mutex) one
> # expose in-flight callbacks to allow future PRs to introduce Java-only
> latency telemetry per-request or just error check/kill of "slow" in-flight
> requests
>
> The possible drawbacks are:
> # slower performance due to GC barriers cost (see the notes on the PR code)
> # slower performance in case of JVM without Unsafe (that means very few)
> The latter issue could be addressed by using the new/proper VarHandle
> features when the Artemis min supported version will move from Java 8 or
> using the same approach on other projects relying on it eg Netty.
> A note about how to correctly benchmark this due to how I've implemented
> async fdatasync: in order to save both LibaioContext and TimedBuffer to
> perform fdatasync batching of writes, I've preferred to simplify the
> LibaioContext: it means that the buffer timeout to be used on broker.xml
> should be obtained by ./artemis perf-journal --sync-writes ie batching writes
> at the speed of the measured fdatasync RTT latency.
> This last behaviour could be changed used a more Apple-to-Apple approach
> although I still think that the beauty of using is Java is exactly to bring
> new features/logics in with a shorter development cycle :)
> We're not in hurry to get this done so that perf-wise this feature could be
> implemented improving performance over the original version too, if possible.
>
>
>
>
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