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From Doron Cohen <DOR...@il.ibm.com>
Subject Re: java.io.IOException: Access is denied on java.io.WinNTFileSystem.createFileExclusively
Date Sun, 27 Aug 2006 17:43:36 GMT
"Jason Polites" <jason.polites@gmail.com> wrote on 27/08/2006 09:36:07:

> I would have thought that simultaneous cross-JVM access to an index was
> outside of scope of the core Lucene API (although it would be great), but
> maybe the file system basis allows for this (?).

Lucene does protect you from mis-accessing its indexes from separate jvms
or even, to a certain extent, separate machines.

>
> I like the idea of catching IOExceptions and returning false.
Conceptually,
> failing to obtain a lock due to any reason can be thought of as the same
> thing, regardless of the reason (so long as its logged).
>
> Seems like the simplest solution too.

I agree with this - as this would be a more correct behavior when the lock
could not be obtained.

However it would not handle the problem that I had, and I think you had too
- that due to some temporary situation in the  OS/FS there is a temporary
inability to perform an action that should be possible - i.e. creating a
new file, or renaming another. Application writers would be "surprised" to
be having to deal with this failure to obtain a lock with no "expected"
reason.

Since this painful situation is evidently possible, and since this is so
frustrating for Lucene users to get their index corrupted in this case, I
still think it is worth the effort of spending some 30ms or so on the rare
occasions that this happen, and retry, trying to bypass this temporary
obstacle.

Did you try that patch? Does it work for you?

I plan to submit an update to that patch later today accommodating your
comments (and others); It will most probably retry for IOExceptions (not
analyzing the exception text); also, it would return false if the *retry*
for obtain() failed with exception.

If you can try out this patch it would be very valuable information to know
whether it prevents the problem or not.

Thanks,
Doron


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