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https://issues.apache.org/jira/browse/CASSANDRA-14922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16737552#comment-16737552
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Joseph Lynch edited comment on CASSANDRA-14922 at 1/8/19 9:53 PM:
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{quote}The patch looks good, and I'd say [~jolynch] let's merge it,
{quote}
Ok, yea I agree let's merge what we have so that the unit tests can pass on
trunk again and we can follow up in CASSANDRA-14969. I've put up a patch
against trunk with what we have so far (including your changes from the demo
branch).
||trunk||
|[0e4460b2e|https://github.com/apache/cassandra/commit/0e4460b2e0996802f02579c104b68ff165522875]|
|[!https://circleci.com/gh/jolynch/cassandra/tree/CASSANDRA-14922.png?circle-token=
1102a59698d04899ec971dd36e925928f7b521f5!|https://circleci.com/gh/jolynch/cassandra/tree/CASSANDRA-14922]|
If I attach a profiler during an intellij "run this test until it fails" mode I
can see that the memory is indeed getting cleaned up:
!MemoryReclaimedFix.png!
was (Author: jolynch):
{quote}The patch looks good, and I'd say [~jolynch] let's merge it,
{quote}
Ok, yea I agree let's merge what we have so that the unit tests can pass on
trunk again and we can follow up in CASSANDRA-14969. I've put up a patch
against trunk with what we have so far (including your changes from the demo
branch).
||trunk||
|[0e4460b2e|https://github.com/apache/cassandra/commit/0e4460b2e0996802f02579c104b68ff165522875]|
|[!https://circleci.com/gh/jolynch/cassandra/tree/CASSANDRA-14922.png?circle-token=
1102a59698d04899ec971dd36e925928f7b521f5!|https://circleci.com/gh/jolynch/cassandra/tree/CASSANDRA-14922]|
If I attach a profiler during an intellij "run this test until it fails" mode I
can see that the memory is indeed getting cleaned up:
!MemoryReclaimedFix.png!
> In JVM dtests need to clean up after instance shutdown
> ------------------------------------------------------
>
> Key: CASSANDRA-14922
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14922
> Project: Cassandra
> Issue Type: Bug
> Components: Test/dtest
> Reporter: Joseph Lynch
> Assignee: Joseph Lynch
> Priority: Minor
> Fix For: 4.0
>
> Attachments: AllThreadsStopped.png, ClassLoadersRetaining.png,
> Leaking_Metrics_On_Shutdown.png, MainClassRetaining.png,
> MemoryReclaimedFix.png, Metaspace_Actually_Collected.png,
> OnlyThreeRootsLeft.png, no_more_references.png
>
>
> Currently the unit tests are failing on circleci ([example
> one|https://circleci.com/gh/jolynch/cassandra/300#tests/containers/1],
> [example
> two|https://circleci.com/gh/rustyrazorblade/cassandra/44#tests/containers/1])
> because we use a small container (medium) for unit tests by default and the
> in JVM dtests are leaking a few hundred megabytes of memory per test right
> now. This is not a big deal because the dtest runs with the larger containers
> continue to function fine as well as local testing as the number of in JVM
> dtests is not yet high enough to cause a problem with more than 2GB of
> available heap. However we should fix the memory leak so that going forwards
> we can add more in JVM dtests without worry.
> I've been working with [~ifesdjeen] to debug, and the issue appears to be
> unreleased Table/Keyspace metrics (screenshot showing the leak attached). I
> believe that we have a few potential issues that are leading to the leaks:
> 1. The
> [{{Instance::shutdown}}|https://github.com/apache/cassandra/blob/f22fec927de7ac291266660c2f34de5b8cc1c695/test/distributed/org/apache/cassandra/distributed/Instance.java#L328-L354]
> method is not successfully cleaning up all the metrics created by the
> {{CassandraMetricsRegistry}}
> 2. The
> [{{TestCluster::close}}|https://github.com/apache/cassandra/blob/f22fec927de7ac291266660c2f34de5b8cc1c695/test/distributed/org/apache/cassandra/distributed/TestCluster.java#L283]
> method is not waiting for all the instances to finish shutting down and
> cleaning up before continuing on
> 3. I'm not sure if this is an issue assuming we clear all metrics, but
> [{{TableMetrics::release}}|https://github.com/apache/cassandra/blob/4ae229f5cd270c2b43475b3f752a7b228de260ea/src/java/org/apache/cassandra/metrics/TableMetrics.java#L951]
> does not release all the metric references (which could leak them)
> I am working on a patch which shuts down everything and assures that we do
> not leak memory.
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