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https://issues.apache.org/jira/browse/CASSANDRA-2333?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13007102#comment-13007102
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Brandon Williams commented on CASSANDRA-2333:
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+1, increased flush queue size is enough to prevent blocking writes at all with
stress and an index.
> Clean up thread pool and queue sizes
> ------------------------------------
>
> Key: CASSANDRA-2333
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2333
> Project: Cassandra
> Issue Type: Bug
> Reporter: Jonathan Ellis
> Assignee: Jonathan Ellis
> Priority: Minor
> Fix For: 0.7.5
>
> Attachments: 2333.txt
>
>
> Most of Cassandra assumes that ThreadPoolExecutor handles tasks by starting
> with Core threads, adding threads up to Max as tasks arrive, then queuing any
> additional. This is not correct:
> {noformat}
> If fewer than corePoolSize threads are running, the Executor always
> prefers adding a new thread rather than queuing.
> If corePoolSize or more threads are running, the Executor always prefers
> queuing a request rather than adding a new thread.
> If a request cannot be queued, a new thread is created unless this would
> exceed maximumPoolSize, in which case, the task will be rejected.
> {noformat}
> CASSANDRA-2178 fixed this in one place but made it worse by default since
> most people run with a single data dir, meaning as soon as you have multiple
> CFs flushing (or a single one with indexes) then you will start blocking
> writes.
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