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https://issues.apache.org/jira/browse/YARN-11843?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18012009#comment-18012009
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ASF GitHub Bot commented on YARN-11843:
---------------------------------------
TaoYang526 commented on PR #7855:
URL: https://github.com/apache/hadoop/pull/7855#issuecomment-3153138028
> @TaoYang526 - It is good catch indeed. Just curious to know - May i know
the use case behind using auto-correction feature ?
@shameersss1 Currently, we don't have a specific use case for the
auto-correction feature. We have always been aware that YARN has an
over-allocation issue, but considered it a minor concern, so no action was
taken. When I discovered YARN-11702, I wanted to take a look and found that it
could resolve most over-allocation issues, except for some in-scheduling cases.
It's sufficient to reduce unnecessary consumption in the scheduling cycle and
we may enable this feature in the future.
> Fix potential deadlock when auto-correction of container allocation is enabled
> ------------------------------------------------------------------------------
>
> Key: YARN-11843
> URL: https://issues.apache.org/jira/browse/YARN-11843
> Project: Hadoop YARN
> Issue Type: Bug
> Components: scheduler
> Affects Versions: 3.5.0
> Reporter: Tao Yang
> Assignee: Tao Yang
> Priority: Major
> Labels: pull-request-available
>
> The feature introduced in YARN-11702 has a potential deadlock issue. When
> enabled, it can cause deadlock when holding application-level write locks
> while trying to acquire queue-level write locks.
>
> Root Cause:
> - autoCorrectContainerAllocation is called while holding application-level
> write locks
> - It directly calls completedContainer() which requires queue-level write
> locks
> {code:java}
> CapacityScheduler#allocate
> --> ...
> application.getWriteLock().lock(); //1. requires app writeLock!!!
> try{
> ...
> AbstractYarnScheduler#autoCorrectContainerAllocation
> --> AbstractYarnScheduler#completedContainer
> --> AbstractYarnScheduler#completedContainerInternal
> --> AbstractLeafQueue#completedContainer
> writeLock.lock() //2. requires queue writeLock!!!
> try{
> ...
> FiCaSchedulerApp#containerCompleted
> //3. requires app writeLock!!!
> }finally{
> writeLock.unlock();
> }
> }finally{
> application.getWriteLock().unlock();
> }{code}
> - This violates lock hierarchy and creates deadlock scenarios, since
> AbstractYarnScheduler#completedContainer could be called from another thread
> during normal container completion operations.
>
> Solution:
> Replace direct completedContainer() calls with asyncContainerRelease() in
> autoCorrectContainerAllocation method.
> Before:
> {code:java}
> completedContainer(rmContainer, ...); // Direct call causes deadlock {code}
> After:
> {code:java}
> asyncContainerRelease(rmContainer); // Async call avoids deadlock {code}
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