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Re: 2.1-dev memory leak?

Subject: Re: 2.1-dev memory leak?
From: Michael McCandless
Date: Fri, 01 Dec 2006 10:00:30 -0500
Otis Gospodnetic wrote:
Yeah, in this case, I'm running out of memory, and open file descriptors are, I 
think, just an indicator that IndexSearchers are not getting closed properly.  
I've already increased the open file descriptors limit, but I'm limited to 2GB 
of RAM on a 32-bit box.

I'll try explicitly closing searchers now....some number of minutes later - 
bingo, that takes care of the leak.

For the curious, this is what I think happened (the app in question is 
http://www.simpy.com/ ).  The app was burning the CPU like crazy (imagine 
nearly double-digit load).  The IO didn't seem crazy (vmstat/iostat didn't show 
much bi/bo).  Still, after some digging around the source code, I found a place 
where I was just going through a few thousand Hits on each search against one 
particular Lucene index.  I fixed that problem (nothing to do with 
IndexSearcher opening/closing), and at the same time I upgraded to Lucene 
2.1-dev.  This fix doubled the performance of the whole service.  Instead of 
handling N requests/second, it was now handling 2-3*N requests/second.  The CPU 
is still running pretty hot, but the service is handling more search traffic.  
My guess is that this increase in performance and throughput simply increased 
the number of different Lucene indices (there are tens of thousands of them per 
box) being searches, and exposed an issue that was either hidden befo
re, or that the JVM was able to handle before, and now it no longer could.  I 
wish I had a little better grip on what exactly happened here, but I've got a 
stable application again.

Thanks for the help!

OK glad to hear all is well again!  Phew.


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