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From David kerber <>
Subject Re: Tomcat - threads / throughput limits?
Date Thu, 08 Nov 2007 16:04:25 GMT
It doesn't answer your question in general, but I increased mine from 
300 to 900 threads on a dual-processor, dual-core machine, and saw 
significantly increased throughput with short, simple requests.  I 
didn't try any in-between settings, though, so I don't know if there 
might be a sweet spot somewhere between those settings, and I don't know 
if going higher would help or not, because the setting it's at right now 
handles the full load with no waiting.

D wrote:
> Hi,
> We have an architecture where we have many tomcat app servers load
> balanced by apache at the front.
> In resolving our current bottleneck i used JProfiler to see what the
> tomcat applications were doing and when under high load there are a lot of
> threads which are blocked on this:
> org.apache.tomcat.util.threads.ThreadPool$
> This suggests that they are spending all their time waiting for tomcat to
> run them, either way they're not runnable anyway.
> Our app pushes through huge quantites of very quick requests - typically
> each request takes a total of 50ms.  We have a limit of 300 connections on
> our AJP connector.
> The point of blocked threads occurs way before we hit that limit.  At the
> same time neither the machine is busy, nor are there any obvious problems
> with memory usage for the instance.
> And indeed; Adding more app servers keeps the load to each one down and
> does resolve the problem - i.e. we can increase throughput.
> So; My question is, is there a reccomended limit to how many threads
> tomcat can handle before it spends more time managing threads than it does
> doing real work?
> Thanks!
> Dan
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