Race condition causes CancelledKeyException in TAsyncClientManager
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Key: THRIFT-836
URL: https://issues.apache.org/jira/browse/THRIFT-836
Project: Thrift
Issue Type: Bug
Components: Compiler (Java)
Reporter: Ning Liang
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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