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From "Michael McCandless (JIRA)" <>
Subject [jira] Commented: (LUCENE-2421) Hardening of NativeFSLock
Date Fri, 30 Apr 2010 19:54:53 GMT


Michael McCandless commented on LUCENE-2421:

bq. Well ... I think they'd appreciate the sleep instead of the immediate exception. Previuosly,
I've been asked by customers to do that in other places. A 100ms sleep is barely noticeable
(being so rare), but an exception definitely is

Yeah I agree we should try to be robust to the "diverse" installations out there, like AVs
that tie up our files.

bq. For the regular lock, we've already agreed we cannot leave it behind as it will prevent
future locking

Wait, how come?  (SimpleFSLF does this, but native gets a "real" lock).

bq.  For the test lock I catch the exception in acquireTestLock and call deleteOnExit() suppressing
the exception.


> Hardening of NativeFSLock
> -------------------------
>                 Key: LUCENE-2421
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Shai Erera
>            Assignee: Shai Erera
>             Fix For: 3.1
>         Attachments: LUCENE-2421.patch
> NativeFSLock create a test lock file which its name might collide w/ another JVM that
is running. Very unlikely, but still it happened a couple of times already, since the tests
were parallelized. This may result in a false exception thrown from release(), when the lock
file's delete() is called and returns false, because the file does not exist (deleted by another
JVM already). In addition, release() should give a second attempt to delete() if it fails,
since the file may be held temporarily by another process (like AntiVirus) before it fails.
The proposed changes are:
> 1) Use ManagementFactory.getRuntimeMXBean().getName() as part of the test lock name (should
include the process Id)
> 2) In release(), if delete() fails, check if the file indeed exists. If it is, let's
attempt a re-delete() few ms later.
> 3) If (3) still fails, throw an exception. Alternatively, we can attempt a deleteOnExit.
> I'll post a patch later today.

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