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https://issues.apache.org/jira/browse/CASSANDRA-7437?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Philip Thompson reopened CASSANDRA-7437:
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        Tester: Philip Thompson

>  Ensure writes have completed after dropping a table, before recycling commit 
> log segments (CASSANDRA-7437)
> -----------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-7437
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7437
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Benedict
>            Assignee: Benedict
>            Priority: Minor
>             Fix For: 2.1 rc3
>
>         Attachments: 7437.log, 7437_test.py
>
>
> I've noticed on unit test output that there are still assertions being raised 
> here, so I've taken a torch to the code path to make damned certain it cannot 
> happen in future 
> # We now wait for all running reads on a column family or writes on the 
> keyspace during a dropCf call
> # We wait for all appends to the prior commit log segments before recycling 
> them
> # We pass the list of dropped Cfs into the CL.forceRecycle call so that they 
> can be markedClean definitely after they have been marked finished
> # Finally, to prevent any possibility of this still happening causing any 
> negative consequences, I've suppressed the assertion in favour of an error 
> log message, as the assertion would break correct program flow for the drop 
> and potentially result in undefined behaviour
> -(in actuality there is the slightest possibility still of a race condition 
> on read of a secondary index that causes a repair driven write, but this is a 
> really tiny race window, as I force wait for all reads after unlinking the 
> CF, so it would have to be a read that grabbed the CFS reference before it 
> was dropped, but hadn't quite started its read op yet).- In fact this is also 
> safe, as these modifications all grab a write op from the Keyspace, which has 
> to happen before they get the CFS, and also because we drop the data before 
> waiting for reads to finish on the CFS.



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