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Posted to commits@cassandra.apache.org by "Philo Yang (JIRA)" <ji...@apache.org> on 2014/12/11 14:28:13 UTC
[jira] [Comment Edited] (CASSANDRA-8459) "autocompaction" on reads
can prevent memtable space reclaimation
[ https://issues.apache.org/jira/browse/CASSANDRA-8459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14242511#comment-14242511 ]
Philo Yang edited comment on CASSANDRA-8459 at 12/11/14 1:27 PM:
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Hi, [~benedict], there is no node in my cluster that is unresponsive now to dump the heap. But there are some hprof files dumped by +HeapDumpOnOutOfMemoryError automatically, are they helpful to you? If so I'll upload one of them.
was (Author: yangzhe1991):
Hi, [~benedict], there is no node in my cluster that is unresponsive to dump the heap. But there are some hprof files dumped by +HeapDumpOnOutOfMemoryError automatically, are they helpful to you? If so I'll upload one of them.
> "autocompaction" on reads can prevent memtable space reclaimation
> -----------------------------------------------------------------
>
> Key: CASSANDRA-8459
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8459
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Benedict
> Assignee: Benedict
> Fix For: 2.1.3
>
> Attachments: 8459.txt
>
>
> Memtable memory reclamation is dependent on reads always making progress, however on the collectTimeOrderedData critical path it is possible for the read to perform a _write_ inline, and for this write to block waiting for memtable space to be reclaimed. However the reclaimation is blocked waiting for this read to complete.
> There are a number of solutions to this, but the simplest is to make the defragmentation happen asynchronously, so the read terminates normally.
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