What version of Solr are you using? Solr1.3 and Lucene 2.4 defaulted to an index reader implementation that had to synchronize, so search operations that are IO "heavy" can't proceed in parallel. You shouldn't see this with 1.4
-Yonik http://www.lucidimagination.com On Tue, Sep 22, 2009 at 4:03 PM, Michael <solrco...@gmail.com> wrote: > Hi, > I have a Solr+Tomcat installation on an 8 CPU Linux box, and I just tried > sending parallel requests to it and measuring response time. I would expect > that it could handle up to 8 parallel requests without significant slowdown > of any individual request. > > Instead, I found that Tomcat is serializing the requests. > > For example, the response time for each of 2 parallel requests is nearly 2 > times that for a single request, and the time for each of 8 parallel > requests is about 4 times that of a single request. > > I am pretty sure this is a Tomcat issue, for when I started 8 identical > instances of Solr+Tomcat on the machine (on 8 different ports), I could send > one request to each in parallel with only a 20% slowdown (compared to 300% > in a single Tomcat.) > > I'm using the stock Tomcat download with minimal configuration changes, > except that I disabled all logging (in case the logger was blocking for each > request, serializing them.) I'm giving 2G RAM to each JVM. > > Does anyone more familiar with Tomcat know what's wrong? I can't imagine > that Tomcat really can't handle parallel requests. >
