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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-669) finalize()-methods of FSDirectory.FSIndexInput and FSDirectory.FSIndexOutput try to close already closed file
Date Tue, 28 Nov 2006 20:12:23 GMT
    [ http://issues.apache.org/jira/browse/LUCENE-669?page=comments#action_12454098 ] 
            
Michael McCandless commented on LUCENE-669:
-------------------------------------------

OK I will try to repro.

In the meantime, I like your theory above!  It seems very plausible that the 2nd close (during
finalize) could [incorrectly] close what was in fact a newly opened descriptor (in use elsewhere).
 This also means this bug is more serious that I had thought (I thought it would just throw
exceptions up to the GC).

One way to be sure this theory is true is to instrument the finalize() to see that indeed
it called close for the second time, and, the close succeeded (instead of throwing the original
exception you saw).  Ie, if this event occurs and then corresponds to the above exception
in the TestStressIndexing unit test, then we've got this explained, and, it's quite serious
since in production this could in theory result in errant IOExceptions like the one above.

> finalize()-methods of FSDirectory.FSIndexInput and FSDirectory.FSIndexOutput try to close
already closed file
> -------------------------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-669
>                 URL: http://issues.apache.org/jira/browse/LUCENE-669
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Store
>            Reporter: Michael Busch
>         Assigned To: Michael Busch
>            Priority: Trivial
>         Attachments: FSDirectory_close_file2.patch
>
>
> Hi all,
> I found a small problem in FSDirectory: The finalize()-methods of FSDirectory.FSIndexInput
and FSDirectory.FSIndexOutput try to close the underlying file. This is not a problem unless
the file has been closed before by calling the close() method. If it has been closed before,
the finalize method throws an IOException saying that the file is already closed. Usually
this IOException would go unnoticed, because the GarbageCollector, which calls finalize(),
just eats it. However, if I use the Eclipse debugger the execution of my code will always
be suspended when this exception is thrown.
> Even though this exception probably won't cause problems during normal execution of Lucene,
the code becomes cleaner if we apply this small patch. Might this IOException also have a
performance impact, if it is thrown very frequently?
> I attached the patch which applies cleanly on the current svn HEAD. All testcases pass
and I verfied with the Eclipse debugger that the IOException is not longer thrown.

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