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https://issues.apache.org/jira/browse/IMPALA-15258?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18104586#comment-18104586
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Michael Smith commented on IMPALA-15258:
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Full stack trace of stuck thread
{code:java}
TID 900328 (exec-finstance (finst:c440df1ea0439a39:4440053500000016)):
@ 0x70c7bca42520 (unknown)
@ 0x70c7bca910d5 (unknown)
@ 0x70c7bca93a01 pthread_cond_wait
@ 0x2b67339 impala::BufferPool::Client::CleanPages()
@ 0x2b6834b impala::BufferPool::Client::TransferReservationTo()
@ 0x2b68405
impala::BufferPool::ClientHandle::TransferReservationTo()
@ 0x3c06404 impala::InitialReservations::Return()
@ 0x3c6e62a impala::ReservationManager::Close()
@ 0x2eb5491 impala::GroupingAggregator::Close()
@ 0x2dc3f50 impala::AggregationNode::Close()
@ 0x2e795b9 impala::ExecNode::Close()
@ 0x3bfc35c impala::FragmentInstanceState::ExecInternal()
@ 0x3bfe0f3 impala::FragmentInstanceState::Exec()
@ 0x3c528db impala::QueryState::ExecFInstance()
@ 0x45428a6 impala::Thread::SuperviseThread()
@ 0x46cd727 thread_proxy {code}
> Query can hang in BufferPool::Client::CleanPages
> ------------------------------------------------
>
> Key: IMPALA-15258
> URL: https://issues.apache.org/jira/browse/IMPALA-15258
> Project: IMPALA
> Issue Type: Bug
> Components: Backend
> Affects Versions: Impala 4.5.0
> Reporter: Michael Smith
> Assignee: Michael Smith
> Priority: Major
>
> With plans produced with CTEs by IMPALA-13533, I've observed the query
> hanging during BufferPool CleanPages. Stack traces showed a thread waiting on
> [https://github.com/apache/impala/blob/master/be/src/runtime/bufferpool/buffer-pool.cc#L713.|https://github.com/apache/impala/blob/master/be/src/runtime/bufferpool/buffer-pool.cc#L713]
> Further logging showed a scenario where {{target_dirty_bytes}} is negative:
> {code:java}
> I20260812 22:48:09.199885 141206 buffer-pool.cc:679]
> 254fc219ed384ebf:227b64f700000010] target_dirty_bytes=-1048576
> reservation=17825792 buffers_allocated_bytes_=1048576 pinned_pages_.bytes()=0
> len=17825792 {code}
> I noticed that {{buffers_allocated_bytes_}} is usually guarded by
> {{{}lock_{}}}, but in
> [DestroyPageInternal|https://github.com/apache/impala/blob/master/be/src/runtime/bufferpool/buffer-pool.cc#L493]
> it's not. Moving that update into the lock seems to fix the hang.
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