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From Jean-frederic Clere <jfcl...@gmail.com>
Subject Re: possible mod_jk "feature"
Date Tue, 22 Aug 2006 21:25:43 GMT
Rainer Jung wrote:

>Jim Jagielski schrieb:
>  
>
>>In a nutshell, there are many cases where Apache httpd and
>>Tomcat are separated by a firewall, and, as such, there
>>isn't a one-to-one direct connection. The firewall
>>will close a connection but one side doesn't
>>know about it.
>>    
>>
>
>I would call this a broken firewall, right?
>
Yep, but that happends ,-(

> This kind of behaviour is
>expected to produce problems for nearl every communication (I don't say,
>we shouldn't provide a workaround).
>
>Still: do you know, what happened in the actual problem case:
>
>- which side of the communication has been shut down by the firewall,
>Apache-FW or FW-Tomcat?
>  
>
I think I have seen a case where the connection Apache-FW was closed 
correctly and the FW-Tomcat just "forgotten".

>- did it reset it, do a full Fin-Ack... or did it just start to silently
>drop packets?
>  
>
I don't know exactly what happends the only thing I have seen is that 
the TC thread stays in the Socket.read() for about 7 minutes and during 
those 7 minutes httpd creates new connections until TC gets out of threads.

>- was keep_alive anbled for the worker? This is a standard socket
>option, that is used to simulate traffic on a connection. The default
>settings for many OSes are interval equals 7200 seconds, so that only
>onc every 2 hours a TCP keep alive packet is being sent. Depending on
>the FW admins idea about idleness, it might be enough to simply lower
>the keep alive interval in the OS TCP configuration. Has this been tried?
>
>  
>
>>As such, new requests create more
>>sockets until TC runs out of threads. mod_jk is
>>not recycling connections as it should, and
>>    
>>
>
>What do you mean by "not recycling"? I think this symptom hasn't been
>reported until now.
>  
>
In my case it is but too late!!!

>  
>
>>setting the various params (eg: connection_pool_timeout)
>>does not solve the problem. It's similar to the old
>>Apache http lingering close problem.
>>
>>http://www.mail-archive.com/tomcat-dev@jakarta.apache.org/msg75444.html
>>is one example of such problems, in which case you
>>responded and agreed that don't reuse is a last resort
>>solution.
>>    
>>
>
>  
>
That is not the problem I have seen!

Cheers

Jean-Frederic

+++ CUT  +++

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