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From Jim Riggs <>
Subject Re: Connector Setting Problem in tomcat 6.0.29
Date Sun, 07 Nov 2010 01:27:00 GMT
On Nov 6, 2010, at 2:17 PM, Christopher Schultz wrote:

>> I believe (if I heard it correctly), either Mark T. or Tim F.
>> explained at ApacheCon this week that the minimum is not immediate.
>> It needs to build up to that level.  So, when you start Tomcat, you
>> won't immediately fire up 150 threads for the executor pool, but once
>>> = 150 threads are created in the process of serving requests, it
>> will always keep a minimum of 150 for you.
> If that's the case, I find that surprising. I always like to avoid
> violating the principle of least surprise. minSpareThreads as a name
> implies to me that those spares are /always/ available, even immediately
> after startup.

Chris -

If you look in org.apache.catalina.core.StandardThreadExecutor, you will see that it is using
a ThreadPoolExecutor.  setMinSpareThreads() calls setCorePoolSize() in the ThreadPoolExecutor.
 If you read the javadoc for ThreadPoolExecutor, specifically the subsections labeled "Core
and maximum pool sizes" and "On-demand construction", you will see that the threads are created
on demand unless you use prestartCoreThread()/prestartAllCoreThreads(), which Tomcat does

So, although it may seem surprising or even counterintuitive, all 150 will not be fired up
on startup.  Perhaps we could add a separate attribute on the Executor (e.g. startThreads)?
 Then Tomcat would have a paradigm similar to httpd's Start(Servers|Threads) and MinSpare(Servers|Threads).
 Any interest in such an attribute?  It would be fairly simple to roll a patch for it...

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