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https://issues.apache.org/jira/browse/CASSANDRA-6079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13775679#comment-13775679
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Oleg Anastasyev commented on CASSANDRA-6079:
--------------------------------------------

Yeah, this makes stall on get() less probable. 

I could measure how big the impact on common case throughout due to rescan of 
thombstones, if you did not performed this measurement earlier.

Yet another idea is to reserve a special thread in CompactionManager for doing 
compactions on batchlog (and possibly hints) CF. This way it at least wouldn't 
delay for a long time.
                
> Memtables flush is delayed when having a lot of batchlog activity, making 
> node OOM
> ----------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6079
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6079
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Oleg Anastasyev
>            Assignee: Oleg Anastasyev
>            Priority: Minor
>             Fix For: 1.2.11, 2.0.2
>
>         Attachments: NoWaitBatchlogCompaction.diff
>
>
> Both MeteredFlusher and BatchlogManager share the same OptionalTasks thread. 
> So, when batchlog manager processes its tasks no flushes can occur. Even 
> more, batchlog manager waits for batchlog CF compaction to finish.
> On a lot of batchlog activity this prevents memtables from flush for a long 
> time, making the node OOM.
> Fixed this by moving batchlog to its own thread and not waiting for batchlog 
> compaction to finish.

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