[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Semb Wever updated CASSANDRA-16668:
---
Fix Version/s: (was: 4.0.x)
(was: 4.0-rc)
4.1
4.0-rc2
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc2, 4.0, 4.1
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ekaterina Dimitrova updated CASSANDRA-16668:
Since Version: (was: 4.0-rc1)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0, 4.0-rc, 4.0.x
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ekaterina Dimitrova updated CASSANDRA-16668:
Fix Version/s: 4.0.x
4.0
Since Version: 4.0-rc1
Source Control Link:
https://github.com/apache/cassandra/commit/8cd02afce972ecaf0e0cf0fe09c610d67d9af9c5
Resolution: Fixed
Status: Resolved (was: Ready to Commit)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0, 4.0-rc, 4.0.x
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ekaterina Dimitrova updated CASSANDRA-16668:
Status: Ready to Commit (was: Review In Progress)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ekaterina Dimitrova updated CASSANDRA-16668:
Reviewers: Andres de la Peña, Ekaterina Dimitrova, Jon Meredith (was:
Andres de la Peña, Jon Meredith)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Andres de la Peña updated CASSANDRA-16668:
--
Reviewers: Andres de la Peña, Jon Meredith, Andres de la Peña (was: Andres
de la Peña, Jon Meredith)
Andres de la Peña, Jon Meredith, Andres de la Peña (was: Andres
de la Peña, Jon Meredith)
Status: Review In Progress (was: Patch Available)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Andres de la Peña updated CASSANDRA-16668:
--
Reviewers: Andres de la Peña, Jon Meredith (was: Jon Meredith)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ekaterina Dimitrova updated CASSANDRA-16668:
Test and Documentation Plan:
[https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01]
Status: Patch Available (was: In Progress)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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[jira] [Updated] (CASSANDRA-16668) Intermittent failure of SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race condition when shrinking maximum pool size to zero
[
https://issues.apache.org/jira/browse/CASSANDRA-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jon Meredith updated CASSANDRA-16668:
-
Bug Category: Parent values: Code(13163)Level 1 values: Bug - Unclear
Impact(13164)
Complexity: Normal
Component/s: Local/Other
Discovered By: Unit Test
Fix Version/s: 4.0-rc
Reviewers: Jon Meredith
Severity: Low
Assignee: Matt Fleming
Status: Open (was: Triage Needed)
> Intermittent failure of
> SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest caused by race
> condition when shrinking maximum pool size to zero
> -
>
> Key: CASSANDRA-16668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16668
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Other
>Reporter: Matt Fleming
>Assignee: Matt Fleming
>Priority: Normal
> Fix For: 4.0-rc
>
>
> A difficult-to-hit race condition exists in
> changingMaxWorkersMeetsConcurrencyGoalsTest when changing the maximum pool
> size from 0 -> 4 which results in the test failing like so:
> {{junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but
> was:junit.framework.AssertionFailedError: Test tasks did not hit max
> concurrency goal expected: but was: at
> org.apache.cassandra.concurrent.SEPExecutorTest.assertMaxTaskConcurrency(SEPExecutorTest.java:198)
> at
> org.apache.cassandra.concurrent.SEPExecutorTest.changingMaxWorkersMeetsConcurrencyGoalsTest(SEPExecutorTest.java:132)}}
> I can hit this issue maybe 2/3 times for every 100 invocations of the unit
> test.
> The issue that causes the failure is that if tasks are still enqueued when
> the maximum pool size is set to zero and if all of the SEPWorker threads
> enter the STOP state before the pool size is bumped to 4, then no SEPWorker
> threads will be spun up to service the task queue. This causes the above
> error.
> Why don't we spin up SEPWorker threads when enqueing tasks? Because of the
> guard logic in addTask:
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/concurrent/SEPExecutor.java#L113,L121]
> In this scenario taskPermits will not be zero (because we have tasks on the
> queue) so we never call {{maybeStartSpinningWorker()}}.
> A trick to make this issue much easier to hit is to insert a
> {{Thread.sleep(500)}} immediately after setting the pool size to zero. This
> has the effect of guaranteeing that all SEPWorker threads will be STOP'd
> before enqueueing more work.
> Here's a fix that attempts to spin up an SEPWorker whenever we grow the
> number of work permits:
> https://github.com/mfleming/cassandra/commit/071516d29e41da9924af24e8002822d3c6af0e01
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