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https://issues.apache.org/jira/browse/CASSANDRA-8815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14324637#comment-14324637
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sankalp kohli commented on CASSANDRA-8815:
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+1
Looks good.
> Race in sstable ref counting during streaming failures
> --------------------------------------------------------
>
> Key: CASSANDRA-8815
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8815
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: sankalp kohli
> Assignee: Benedict
> Fix For: 2.0.13
>
> Attachments: 8815.txt
>
>
> We have a seen a machine in Prod whose all read threads are blocked(spinning)
> on trying to acquire the reference lock on stables. There are also some
> stream sessions which are doing the same.
> On looking at the heap dump, we could see that a live sstable which is part
> of the View has a ref count = 0. This sstable is also not compacting or is
> part of any failed compaction.
> On looking through the code, we could see that if ref goes to zero and the
> stable is part of the View, all reader threads will spin forever.
> On further looking through the code of streaming, we could see that if
> StreamTransferTask.complete is called after closeSession has been called due
> to error in OutgoingMessageHandler, it will double decrement the ref count of
> an sstable.
> This race can happen and we see through exception in logs that closeSession
> was triggered by OutgoingMessageHandler.
> The fix for this is very simple i think. In StreamTransferTask.abort, we can
> remove a file from "files” before decrementing the ref count. This will avoid
> this race.
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