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From André Warnier ...@ice-sa.com>
Subject Re: apache/tomcat communication issues (502 response)
Date Thu, 09 Apr 2009 14:27:58 GMT
Caldarale, Charles R wrote:
[...]
> 
> When you catch threads doing socket I/O, they are almost always waiting for input from
the client.  If you're using keep-alives (highly likely), that's the normal state of a thread.
 This likely means you don't have enough requests coming in to keep the threads you already
have busy; adding more threads won't change that.
> 
If I may add something :
During the recent ApacheCON, one of the gurus there made a comment 
related to KeepAlive, which as far as I recall was to the following 
effect : the default KeepAlive settings of webservers (many requests, 
long duration) are basically a relic of the past, when the setup and 
teardown of a TCP connection tended to be significant in terms of 
resources, compared to the time actually spent responding to the 
request.  With modern servers, it is worth having a good look at the 
settings, and in most cases reduce them rather drastically.
That is because a KeepAlive connection will keep a server child (or 
thread) tied to that particular client connection, until the KeepAlive 
expires, probably doing nothing most of the time.  It would be better in 
most cases to have the client re-build a connection more often, and 
allow those server children/threads to take care of other requests in 
the meantime.


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