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https://issues.apache.org/jira/browse/IMPALA-8020?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tim Armstrong updated IMPALA-8020:
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Target Version: Product Backlog (was: Impala 3.3.0)
I was running stress tests for a while and I never saw the process memory
consumption get much over 90% of the process memory limit. So I think this is a
flaw in the memory management scheme but with limited practical implications.
> Process memory consumption does not include unused reservations
> ---------------------------------------------------------------
>
> Key: IMPALA-8020
> URL: https://issues.apache.org/jira/browse/IMPALA-8020
> Project: IMPALA
> Issue Type: Bug
> Components: Backend
> Reporter: Tim Armstrong
> Assignee: Tim Armstrong
> Priority: Major
> Labels: resource-management
>
> This is being split out from IMPALA-7446, since it's a somewhat separate
> issue.
> The issue is that the process memory consumption only accounts for system
> memory allocated from the buffer pool, not for reservations that have not
> been fulfilled yet. Reserved allocations do *not* check the process memory
> limit before going through, so it's possible that the same memory could be
> committed both to a non-reserved allocation and a reserved allocation.
> In practice this seems unlikely to cause any real symptoms - it would require:
> * the process to be near its memory limit
> * a large amount of unused reservation, not offset by free buffers or clean
> pages.
> * a quick spike in the amount of reservation used
> This *could* result in the process going significantly over its memory limit
> before queries start to fail and free memory.
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