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Posted to issues-all@impala.apache.org by "Sahil Takiar (Jira)" <ji...@apache.org> on 2020/04/09 22:36:00 UTC
[jira] [Commented] (IMPALA-9638) Don't create unnecessary threads
in executor-only impalads
[ https://issues.apache.org/jira/browse/IMPALA-9638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17080044#comment-17080044 ]
Sahil Takiar commented on IMPALA-9638:
--------------------------------------
Noticed this while looking into IMPALA-9609, so linking the two.
> Don't create unnecessary threads in executor-only impalads
> ----------------------------------------------------------
>
> Key: IMPALA-9638
> URL: https://issues.apache.org/jira/browse/IMPALA-9638
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Reporter: Sahil Takiar
> Priority: Major
>
> Looking through the code for ImpalaServer, it looks like there are several threads / thread-pools that are started on executor-only impalads, but don't actually do anything:
> * The "cancellation-worker" threadpool (ImpalaServer::CancelFromThreadPool)
> * The "session-maintenance" thread (ImpalaServer::SessionMaintenance)
> * The "query-expirer" thread (ImpalaServer::ExpireQueries)
> * The "unresponsive-backend-thread" thread (ImpalaServer::UnresponsiveBackendThread)
> * The code to start ImpalaInternalService might be dead code, but maybe we should just delete it since the ImpalaInternalService doesn't exist anymore
> Confirmed this my creating a cluster with dedicated coordinator and getting a thread dump of an executor, which showed the following:
> {code:java}
> Thread 16 (Thread 0x7fe96fe57700 (LWP 8721)):
> #0 0x00007fea1ad20360 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
> No symbol table info available.
> #1 0x0000000001ce4423 in impala::ConditionVariable::Wait (this=0x110b3370, lock=...) at /home/stakiar/Impala/be/src/util/condition-variable.h:49
> mutex = 0x110b3348
> #2 0x0000000002469f6a in impala::ImpalaServer::SessionMaintenance (this=0x110b3200) at /home/stakiar/Impala/be/src/service/impala-server.cc:2055
> timeout_lock = {_M_device = 0x110b3348, _M_owns = true}
> now = 140640581412928
> expired_cnt = 0 {code}
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