lucene file locking question

[John Wang <jo...@gmail.com>]

Hi folks:

      My application builds a super-index around the lucene index,
e.g. stores some additional information outside of lucene.

       I am using my own locking outside of the lucene index via
FileLock object in the jdk1.4 nio package.

       My code does the following:

FileLock lock=null;
try{
        lock=myLockFileChannel.lock();

        indexing into lucene;

        indexing additional information;

}

finally{
      try{
          commit lucene index by closing the IndexWriter instance.
      }
      finally{
        if (lock!=null){
           lock.release();
        }
      }
}


Now here is the weird thing, say I terminate the process in the middle
of indexing, and run the program again, I would get a "Lock obtain
time out" exception, as long as you delete the stale lock file, the
index remains uncorrupted.

However, if I turn lucene file lock off since I have a lock outside it anyways, 
(by doing: 
static{
    System.setProperty("disableLuceneLocks","true");
  }
)

and do the same thing. Instead I get an unrecoverable corrupted index.

Does lucene lock really guarentee index integrity under this kind of
abuse or am I just getting lucky?
If so, can someone shine some light on how?

Thanks in advance

-John

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Re: lucene file locking question

[ya...@yahoo.com]

Disabling locking is only recommended for read-only indexes that
aren't being modified.  I think there is a comment in the code
about a good example of this being an index you read off of a
CD-ROM.

--- John Wang <jo...@gmail.com> wrote:

> Hi folks:
> 
>       My application builds a super-index around the lucene
> index,
> e.g. stores some additional information outside of lucene.
> 
>        I am using my own locking outside of the lucene index
> via
> FileLock object in the jdk1.4 nio package.
> 
>        My code does the following:
> 
> FileLock lock=null;
> try{
>         lock=myLockFileChannel.lock();
> 
>         indexing into lucene;
> 
>         indexing additional information;
> 
> }
> 
> finally{
>       try{
>           commit lucene index by closing the IndexWriter
> instance.
>       }
>       finally{
>         if (lock!=null){
>            lock.release();
>         }
>       }
> }
> 
> 
> Now here is the weird thing, say I terminate the process in
> the middle
> of indexing, and run the program again, I would get a "Lock
> obtain
> time out" exception, as long as you delete the stale lock
> file, the
> index remains uncorrupted.
> 
> However, if I turn lucene file lock off since I have a lock
> outside it anyways, 
> (by doing: 
> static{
>     System.setProperty("disableLuceneLocks","true");
>   }
> )
> 
> and do the same thing. Instead I get an unrecoverable
> corrupted index.
> 
> Does lucene lock really guarentee index integrity under this
> kind of
> abuse or am I just getting lucky?
> If so, can someone shine some light on how?
> 
> Thanks in advance
> 
> -John
> 
>
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> 
> 


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