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From Simone Caruso <i...@simonecaruso.com>
Subject Re: [users@httpd] Intermittent mod_proxy_ajp error - APR does not understand this error code: proxy: dialog
Date Sun, 29 Jul 2012 10:04:37 GMT
On 25/07/2012 14:23, Carlucci, Tony wrote:
>> -----Original Message-----
>> From: Rainer Jung [mailto:rainer.jung@kippdata.de]
>> Sent: Wednesday, July 25, 2012 5:00 AM
>> To: users@httpd.apache.org
>> Subject: Re: [users@httpd] Intermittent mod_proxy_ajp error - APR does not
>> understand this error code: proxy: dialog
>>
>> On 23.07.2012 20:36, Carlucci, Tony wrote:
>>> Hello, I’ve been trying to track down an intermittent problem with a
>>> Java web application that is running on tcServer fronted by Apache HTTP
>>> Server.    We get intermittent “Server Unavailable / HTTP 500” errors,
>>> and when we do see them, there is the same set of log statements written
>>> to the Apache HTTP Server error log:
>>>
>>> [Mon Jul 23 10:03:15 2012] [error] (70014)End of file found:
>>> ajp_ilink_receive() can't receive header
>>>
>>> [Mon Jul 23 10:03:15 2012] [error] ajp_read_header: ajp_ilink_receive failed
>>>
>>> [Mon Jul 23 10:03:15 2012] [error] (120006)APR does not understand this
>>> error code: proxy: dialog to 127.0.0.1:7071 (127.0.0.1) failed
>>>
>>> We are not seeing any error messages in the tcServer logs.
>>>
>>> I believe the issue is with the mod_proxy_ajp module but it’s been very
>>> difficult tracking down what exactly the problem is.   What’s
>>> interesting is that this Apache / tcServer configuration is used with
>>> other applications that work just fine and never have the intermittent
>>> 500 error.   We also can run our application strictly in Tomcat (no
>>> Apache front) without any intermittent errors.
>>>
>>> We haven’t ruled out that there could be something in our Java
>>> application code that is causing this, in combination with the
>>> mod_proxy_ajp module, but we have hit a wall as to what this issue could
>>> be.  Has anyone else experienced a similar intermittent issue combined
>>> with the above error messages?  Below is a copy of the error log and
>>> some configuration settings.
>> You might want to check the following discussion thread:
>>
>>    http://marc.info/?t=123905265500007&r=1&w=2
>>
>> To actually narrow down the cause I would:
>>
>> - use ping as mentioned in the thread
>> - check whether the timeout you have set on the Tomcat connector is
>> roughly the same as used by mod_proxy_ajp
>> - check whether it looks like happening mostly for the same URL, then it
>> is more likely a servlet issue
>> - if it happens often enough sniff the traffic between Apache and Tomcat
>> and then check the packet details for one of the broken requests. For
>> this to work you might need to move Tomcat away from localhost.
>>
> Thanks for the suggestions Rainer, I'll give these a try.
>
> Tony


forget mod_proxy_ajp, use mod_jk

-- 
Simone Caruso
IT Consultant
+39 349 65 90 805


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