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https://issues.apache.org/jira/browse/CASSANDRA-21657?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Semb Wever updated CASSANDRA-21657:
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Bug Category: Parent values: Degradation(12984)
Complexity: Low Hanging Fruit
Discovered By: Code Inspection
Fix Version/s: 6.0.x
5.0.x
7.x
Severity: Low
Status: Open (was: Triage Needed)
> The hints write buffer is not released when the write executor shuts down
> -------------------------------------------------------------------------
>
> Key: CASSANDRA-21657
> URL: https://issues.apache.org/jira/browse/CASSANDRA-21657
> Project: Apache Cassandra
> Issue Type: Bug
> Components: Consistency/Hints
> Reporter: Michael Semb Wever
> Priority: Normal
> Fix For: 6.0.x, 5.0.x, 7.x
>
>
> {{HintsWriteExecutor}} allocates a 256 KiB direct buffer that every write
> task shares:
> {code:java}
> writeBuffer = ByteBuffer.allocateDirect(WRITE_BUFFER_SIZE);
> {code}
> {{shutdownBlocking}} shuts the executor down and leaves the buffer allocated.
> A process that shuts the hints service down and starts it again loses 256 KiB
> of direct memory each time. The in-JVM test framework does exactly that, once
> per instance restart, so a long dtest run holds direct memory that no
> instance can use.
> A node shutdown in production ends the process, so the priority is Low; the
> cost falls on the test framework and on any other caller that restarts the
> service in one process.
> The patch releases the buffer with {{FileUtils.clean}} after the executor
> terminates. The release waits for termination, because a write task that
> still runs holds the buffer, and a shutdown that gives up after its minute
> reports the buffer it keeps rather than freeing memory a task may write to.
> Patch:
> [mck/upstream/hints-write-buffer-release/5.0|https://github.com/thelastpickle/cassandra/tree/mck/upstream/hints-write-buffer-release/5.0]
> Provenance:
> [00003d27fa|https://github.com/datastax/cassandra/commit/00003d27faf2241245436d9440d740e1cd18aaa8]
> by [~jlewandowski]. That commit releases the buffer in a {{finally}} block
> and carries further work on the buffer pool and on the in-JVM instance
> shutdown, which this patch leaves out. The {{finally}} block frees the buffer
> even when a write task is still running, so this patch tests the termination
> result instead, and adds the regression test the commit lacks.
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