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From Rainer Jung <>
Subject Re: Apache/mod_jk serves random files from tomcat
Date Tue, 15 Jul 2008 13:36:12 GMT
Hi David,

dave.smith schrieb:
> Hi Rainer,
> Thanks a lot for the reply.
> I am using Tomcat 5.5.25 (rpm from  CentOS Linux 2.6.18.
> httpd was compiled in prefork mode. The prefork settings are:
> StartServers       8
> MinSpareServers    5
> MaxSpareServers   20
> ServerLimit      256
> MaxClients       256
> MaxRequestsPerChild  4000
> I have setup JMeter to run against a test environment, but was unable to
> reproduce.  These random responses occur in production about once every week
> or so/more.  The problem will often (temporarily) correct itself, but
> sometimes I will need to restart httpd if the problem persists -- restarting
> tomcat also works to temporarily correct the problem.
> The only thing strange that I see in my logs are in the test_client.log:
> WARNING: Exception thrown whilst processing POSTed parameters 
> Socket read failed
>         at
>         ...

Thanks for the information. What is "test_client.log"? It looks like a 
Tomcat log file? Could you also post a larger part of the stack, or do 
you only get one line?

Would you be able to do the following two things, maybe not both at the 
same time:

- disable the apr connector (
- upgrade jk to 1.2.26

Concerning the apr connector: If you are using OpenSSL with apr and 
Tomcat or you have some similar reason you really need it, then don't 
switch. But if you use it without a very specific reason, disabling it 
for a week or two would help us isolate the problem.

Concerning mod_jk upgrade: That should be very easy, apart from the 
following: if your httpd uses VirtualHost in the configuration, you have 
to include your JkMount inside the VirtualHost, not in the global part, 
or you add JkMountCopy On to the VirtualHost.



> Rainer Jung-3 wrote:
>> dave.smith schrieb:
>>>> Wow. That's weird. Is Tomcat serving the file, or is httpd serving it?
>>> Not too weird.  I am experiencing the same thing with Tomcat 5.5 and
>>> mod_jk
>>> 1.2.23.  I have Tomcat serving everything.
>>> I am also using a load balancer that sends an OPTION every 2 seconds to
>>> each
>>> web server to make sure that the server is alive.
>>> This intermittent random response issue is really killing me.
>> Could you please also add some info:
>> Tomcat version?
>> And from my previous mail:
>> What's you platform and which httpd MPM (prefork orworker or something 
>> else) do you use? For some platforms (e.g. AIX) the detection of 
>> multi-threading in httpd during mpod_jk build-time was broken. Starting 
>> with 1.2.24 we build always including multi-thread support unless 
>> explicitely stated via a configure option. If you 1.2.23 build is not 
>> thread safe, but your httpd uses threads (like with worker mpm), then 
>> such trouble is possible, although more likely you would see crashes 
>> etc. For most platforms like Linux and Solaris the threading detection 
>> was OK already before 1.2.24.
>> Another possible (but not very likely) cause could be bug 44494 of 
>> Tomcat 6.0.16/5.5.26 which under certain circumstances could leave data 
>> in the request object after request handling completed. You could try 
>> either downgrading to 6.0.15/5.5.25 or upgrading to the soon to be 
>> expected 6.0.17/5.5.27.
>> I would also add the access log on the Tomcat side. If you find the same 
>> phenomenon there, then it's unlikely, that httpd/mod_jk are responsible 
>> and the reason should be inside Tomcat or the webapp.
>> Can you reproduce the problem on a test system?
>> Regards,
>> Rainer

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