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From "Bill Graham (JIRA)" <j...@apache.org>
Subject [jira] Created: (PIG-1313) PigServer leaks memory over time
Date Mon, 22 Mar 2010 16:59:27 GMT
PigServer leaks memory over time

                 Key: PIG-1313
                 URL: https://issues.apache.org/jira/browse/PIG-1313
             Project: Pig
          Issue Type: Bug
            Reporter: Bill Graham

When {{PigServer}} runs it creates temporary files using the {{FileLocalizer.getTemporaryPath(..)}}.
This static method creates and returns a handle to a temporary file (as an instance of {{ElementDescriptor}}).
The {{ElementDescriptors}} returned by this method are kept on a static {{Stack}} named {{toDelete}}.
The items on {{toDelete}} get removed by the {{FileLocalizer.deleteTempFile()}} method.

The only place in the code where I see {{FileLocalizer.deleteTempFile()}} called is in the
Main class. {{PigServer}} does not call that method though, so a long-running VM that repeatedly
uses instances of {{PigServer}} to run jobs will leak memory via {{toDelete}}.

One suggested fix is to have {{PigServer.shutdown()}} call {{FileLocalizer.deleteTempFile()}},
but this would cause problems in a multi-threaded environment, since it seems {{ElementDescriptors}}
are pushed onto the {{toDelete}} stack before they're used, not once they're done with. With
this approach, running multiple instances of {{PigServer}} in separate threads could cause
one completed job to clobber the other's still-in-use temp files.

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