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From Daniel Andersson <>
Subject Re: Help optimizing
Date Tue, 06 May 2008 21:54:34 GMT

On May 6, 2008, at 4:00 AM, Mike Klaas wrote:

> On 3-May-08, at 10:06 AM, Daniel Andersson wrote:
>> How do I optimize Solr to better use all the RAM? I'm using java6,  
>> 64bit version, and start Solr using:
>> java -Xmx7500M -Xms4096M -jar start.jar
>> But according to top it only seems to be using 7.7% of the memory  
>> (around 600 MB).
> Don't try to give Solr _all_ the memory on the system.  Solr depends  
> on the index existing in the OS's disk cache (this is "cached" in  
> top).  You should have at least 2 GB memory for a 3.5GB index,  
> depending on how much of the index is stored (best is of course to  
> have 3.5GB available so it can be cached completely).
> Solr will require a wide distribution of queries to "warm up" (get  
> the index in the OS disk cache).   This is automatically prioritize  
> the "hot spots" in the index.  If you want to load the whole thing  
> 'cd datadir; cat * > /dev/null' works, but I don't recommend relying  
> on that.

Ah. Have given it 4 GB of RAM now (Xmx=4 GB, Xms=2 GB)

>> Most queries are for make_id + model_id or city + state and almost  
>> all of the queries are ordered by datetime_found (newest -> oldest).
> How many documents match, typically?  How many documents are  
> returned, typically?  How often do you commit() [I suspect  
> frequently, based on the problems you are having]?

Average documents matched/found: 6427
Only return 10 documents per page

Commit every 10,000 documents. Tried it at 100,000 with 2 GB of ram (1  
GB dedicated to Solr) and it just gave me OutOfMemory every time.  
Haven't tried increasing it since moving it to this new server.


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