[jira] Closed: (THRIFT-836) Race condition causes CancelledKeyException in TAsyncClientManager

["Bryan Duxbury (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/THRIFT-836?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bryan Duxbury closed THRIFT-836.
--------------------------------

    Resolution: Fixed

I just committed this. Thanks for the patch, Ning!

> Race condition causes CancelledKeyException in TAsyncClientManager
> ------------------------------------------------------------------
>
>                 Key: THRIFT-836
>                 URL: https://issues.apache.org/jira/browse/THRIFT-836
>             Project: Thrift
>          Issue Type: Bug
>          Components: Library (Java)
>            Reporter: Ning Liang
>            Assignee: Bryan Duxbury
>            Priority: Blocker
>             Fix For: 0.4
>
>         Attachments: async_client_catch_all.diff, async_thrift.diff, async_thrift_catch_except.diff
>
>
> Currently, TAsyncClientMethod cancels its selection key on a successful method call. The current model assumes the key goes away and the client gets a new key on the next Selector registration, which is incorrect - the cancelled key can hang around, with the implication that the developer needs to check key.isValid() on the next selector action, which TAsyncClientMethod currently does. However, if the developer re-uses the client for another call, you can get a CancelledKeyException from the Selector#register call, which crashes the SelectorThread. This occurs once you have sufficient concurrency on the Selector - cancelled key cleanup takes longer, so we hit this condition.
> Attached is a patch with fix and regression test. Summary of fix:
> 1) Don't cancel() the key after a successful method call.
> 2) Catch CancelledKeyException in the SelectorThread, so the manager can't die.
> 3) Add an onError method to TAsyncMethodCall, so that the SelectorThread can notify the client of an error on selector registration.

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