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From robert engels <reng...@ix.netcom.com>
Subject Re: After kill -9 index was corrupt
Date Mon, 11 Sep 2006 20:06:45 GMT
I am not stating that you did not uncover a problem. I am only  
stating that it is not due to OS level caching.

Maybe your sequence of events triggered a reread of the index, while  
some thread was still writing. The reread sees the 'unused segments'  
and deletes them, and then the other thread writes the updated  
'segments' file.

 From what you state, it seems that you are using some custom code  
for index writing? (Maybe the NewIndexModified stuff)? Possibly there  
is an issue there. Do you maybe have your own cleanup code that  
attempts to remove unused segments from the directory? If so, that  
appears to be the likely culprit to me.

On Sep 11, 2006, at 2:56 PM, Chuck Williams wrote:

> robert engels wrote on 09/11/2006 07:34 AM:
>> A kill -9 should not affect the OS's writing of dirty buffers
>> (including directory modifications). If this were the case, massive
>> system corruption would almost always occur every time a kill -9 was
>> used with any program.
>>
>> The only thing a kill -9 affects is user level buffering. The OS
>> always maintains a consistent view of directory modifications and or
>> file modification that were requesting by programs.
>>
>> This entire discussion is pointless.
>>
> Thanks everyone for your analysis.  It appears I do not have any
> explanation.  In my case, the process was in gc-limbo due to the  
> memory
> leak and having butted up against its -Xmx.  The process was kill -9'd
> and then restarted.  The OS never crashed.  The server this is on is
> healthy; it has been used continually since this happened without  
> being
> rebooted and no file system or any other issues.  When the process was
> killed, one thread was merging segments as part of flushing the ram
> buffer while closing the index, due to the prior kill -15.  When  
> Lucene
> restarted, the segments file contained a segment name for which there
> were no corresponding index data files.
>
> Chuck
>
>
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