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From André Warnier ...@ice-sa.com>
Subject Re: Apache httpd 1.3 and connection pooling
Date Fri, 30 Jan 2009 15:09:21 GMT
Arne Riecken wrote:
> If I understood right, Apache httpd 1.3 is not multi threaded but can
> consist of multiple processes. And one Apache process has a connection pool
> size of 1 that should not be changed. So is there a kind of pool of
> 1-connection-pools ? 
That I don't really know, but it sounds right.
Or rather, there are only a limited number of Apache children available 
to process requests, one request per child.

Is it right that it does not make sense then for mod_jk
> to have more apache processes than backend workers?

That sounds correct to me. As I understand it,
1 request to Apache --> 1 Apache child process + mod_jk --> 1 connection 
to Tomcat --> 1 Connector thread in Tomcat
until the request is processed by Tomcat and the response goes back.

Any additional Apache child + mod_jk sending an additional request to 
Tomcat when all Tomcat threads are already busy, would just be queued up 
in the Connector's TCP backup queue, until a thread is available to 
service it.  If the queue itself fills up, any additional request will 
just be dropped.

In other words, if Tomcat's <Connector maxThreads="150" ..>, there 
should not be any real advantage in having Apache's MaxClients > 150.

Unless there is a slight advantage in letting a request through and wait 
in the Connector's TCP backup queue, rather than delaying it at the 
Apache level.
Maybe a real expert here can answer that ?


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