[jira] [Created] (CASSANDRA-12358) Slow PostFlush execution due to 2i flushing can cause near OOM to OOM

["Ariel Weisberg (JIRA)" <ji...@apache.org>]

Ariel Weisberg created CASSANDRA-12358:
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             Summary: Slow PostFlush execution due to 2i flushing can cause near OOM to OOM
                 Key: CASSANDRA-12358
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12358
             Project: Cassandra
          Issue Type: Bug
          Components: Core
            Reporter: Ariel Weisberg
            Assignee: Ariel Weisberg
             Fix For: 3.10


2i can be slow to flush for a variety of reasons. Potentially slower than the rate at which Memtables can ingest and flush data. If this occurs the heap fills up with Memtables that are waiting for PostFlush to run.

This occurs because reclaiming the memory is done before PostFlush runs.

I will post a branch that has the reclaim memory task run after PostFlush has completed. As far as I can tell this is safe and correct since the memory is committed up until that point.

It's not clear to me if PostFlush has to bind the Memtables or not. I suspect it does, but I'm not sure if that is a route I should go down.



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