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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-665) temporary file access denied on Windows
Date Fri, 27 Oct 2006 23:57:20 GMT
    [ http://issues.apache.org/jira/browse/LUCENE-665?page=comments#action_12445301 ] 
            
Michael McCandless commented on LUCENE-665:
-------------------------------------------

Doron, I finally managed to see an exception like yours above, but I had to have the Windows
Explorer open to the index directory and then right click on files, while the indexing was
happening.  Once I could get this to happen I then found that the lock-less patch ( LUCENE-701
) plus native locking *seemed* to prevent the issue (I think it should because no file renaming
is done).  But given how hard it is for me to reproduce this, can you try in your area the
combination of lock-less and native locking to see if that prevents this issue?  Thanks.

> temporary file access denied on Windows
> ---------------------------------------
>
>                 Key: LUCENE-665
>                 URL: http://issues.apache.org/jira/browse/LUCENE-665
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Store
>    Affects Versions: 2.0.0
>         Environment: Windows
>            Reporter: Doron Cohen
>         Attachments: FSDirectory_Retry_Logic.patch, FSDirs_Retry_Logic_3.patch, FSWinDirectory.patch,
FSWinDirectory_26_Sep_06.patch, Test_Output.txt, TestInterleavedAddAndRemoves.java
>
>
> When interleaving adds and removes there is frequent opening/closing of readers and writers.

> I tried to measure performance in such a scenario (for issue 565), but the performance
test failed  - the indexing process crashed consistently with file "access denied" errors
- "cannot create a lock file" in "lockFile.createNewFile()" and "cannot rename file".
> This is related to:
> - issue 516 (a closed issue: "TestFSDirectory fails on Windows") - http://issues.apache.org/jira/browse/LUCENE-516

> - user list questions due to file errors:
>   - http://www.nabble.com/OutOfMemory-and-IOException-Access-Denied-errors-tf1649795.html
>   - http://www.nabble.com/running-a-lucene-indexing-app-as-a-windows-service-on-xp%2C-crashing-tf2053536.html
> - discussion on lock-less commits http://www.nabble.com/Lock-less-commits-tf2126935.html
> My test setup is: XP (SP1), JAVA 1.5 - both SUN and IBM SDKs. 
> I noticed that the problem is more frequent when locks are created on one disk and the
index on another. Both are NTFS with Windows indexing service enabled. I suspect this indexing
service might be related - keeping files busy for a while, but don't know for sure.
> After experimenting with it I conclude that these problems - at least in my scenario
- are due to a temporary situation - the FS, or the OS, is *temporarily* holding references
to files or folders, preventing from renaming them, deleting them, or creating new files in
certain directories. 
> So I added to FSDirectory a retry logic in cases the error was related to "Access Denied".
This is the same approach brought in http://www.nabble.com/running-a-lucene-indexing-app-as-a-windows-service-on-xp%2C-crashing-tf2053536.html
- there, in addition to the retry, gc() is invoked (I did not gc()). This is based on the
*hope* that a access-denied situation would vanish after a small delay, and the retry would
succeed.
> I modified FSDirectory this way for "Access Denied" errors during creating a new files,
renaming a file.
> This worked fine for me. The performance test that failed before, now managed to complete.
There should be no performance implications due to this modification, because only the cases
that would otherwise wrongly fail are now delaying some extra millis and retry.
> I am attaching here a patch - FSDirectory_Retry_Logic.patch - that has these changes
to FSDirectory. 
> All "ant test" tests pass with this patch.
> Also attaching a test case that demostrates the problem - at least on my machine. There
two tests cases in that test file - one that works in system temp (like most Lucene tests)
and one that creates the index in a different disk. The latter case can only run if the path
("D:" , "tmp") is valid.
> It would be great if people that experienced these problems could try out this patch
and comment whether it made any difference for them. 
> If it turns out useful for others as well, including this patch in the code might help
to relieve some of those "frustration" user cases.
> A comment on state of proposed patch: 
> - It is not a "ready to deploy" code - it has some debug printing, showing the cases
that the "retry logic" actually took place. 
> - I am not sure if current 30ms is the right delay... why not 50ms? 10ms? This is currently
defined by a constant.
> - Should a call to gc() be added? (I think not.)
> - Should the retry be attempted also on "non access-denied" exceptions? (I think not).
> - I feel it is somewhat "woodoo programming", but though I don't like it, it seems to
work... 
> Attached files:
> 1. TestInterleavedAddAndRemoves.java - the LONG test that fails on XP without the patch
and passes with the patch.
> 2. FSDirectory_Retry_Logic.patch
> 3. Test_Output.txt- output of the test with the patch, on my XP. Only the createNewFile()
case had to be bypassed in this test, but for another program I also saw the renameFile()
being bypassed.
> - Doron

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