Paul Brannan created KUDU-3763:
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Summary: Kudu master spending a lot of time in
ExtractTabletsToProcess
Key: KUDU-3763
URL: https://issues.apache.org/jira/browse/KUDU-3763
Project: Kudu
Issue Type: Bug
Affects Versions: 1.18.1
Reporter: Paul Brannan
I've noticed for a while that kudu-master is using cpu when idle. When I run
{{{}perf top{}}}, I see:
{{34.01% kudu-master [.]
kudu::master::CatalogManager::ExtractTabletsToProcess
26.07% kudu-master [.] kudu::subtle::RefCountedThreadSafeBase::AddRef
25.04% libpthread-2.31.so [.] pthread_mutex_trylock
3.30% libpthread-2.31.so [.] pthread_mutex_unlock}}
This is somewhat expected – background tasks do run periodically, after all –
but it is surprising that so much time is spent in this background task than
the others.
Per {{{}/varz{}}}, {{--catalog_manager_bg_task_wait_ms}} is set at the default
of 1000. Increasing this default would make the problem less noticeable, but >
100ms every second to run a background task is not ideal.
There is a TODO in {{CatalogManager::ExtractTabletsToProcess}} suggesting ways
to avoid the lock.
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