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From Mark Thomas <ma...@apache.org>
Subject Re: Tomcat stops responding
Date Sun, 19 Dec 2010 17:43:33 GMT
On 17/12/2010 12:52, K J.Sreekumar wrote:
> Hello All,
> 
> We are hitting on a weird problem with tomcat 6 production server (which is
> a serious concern for us now). Hoping to get help from the you guys
> 
> This is the problem -
> 
>    1. Our tomcat 6 server (version 6.0.29) does not respond after working
>    for a couple of days. Browsers are unable to find application URLs (which
>    were previously processed normally).
>    2. The logs does not show any error.
>    3. There are only a total of 50-60 threads in the thread dump, mostly in
>    WAIT state. Also, it does not show any BLOCKING or LOCKED threads.
>    4. Memory utilization was 400MB only
>    5. TOMCAT restart does not fix the problem. The machine needs to be
>    restarted to resume normal operation.
>    6. Netstat did not reveal any extraneous connections
> 
> We are running Tomcat 6.0.29 on the following platform -
> 
> OS: Windows server 2003 R2 Enterprise Edition SP2
> Hardware: Intel Xeon L5520 2.27 GHz (16 CPU threads )
> 
> The server.xml we are using has been attached with this mail.
> 
> Have anybody here faced similar issue before ?

Frequently.

Usually a mis-match between the number of threads configured in httpd
and the number of threads configured in Tomcat. Since mod_jk and
mod_proxy use persistent connections by default and the BIO connector
uses one thread per connection then if httpd has more threads configured
you can eventually reach a state where all Tomcat's threads have been
allocated and  the next request blocks.

There are two possible approaches.
1. Tune the time-outs
2. Disable connection re-use

I'd go with 2 - it takes much less time to set up. Ignore the dire
warnings in the docs. Most users don't notice the difference.

Mark

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