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From Rainer Jung <rainer.j...@kippdata.de>
Subject Re: Unrecoverable error 200, request failed
Date Sun, 28 Oct 2007 12:23:13 GMT
Hi,

usually those info messages indicate, that the request took to long, so 
the user in front of the browser did a retry or back or something 
similar. In this case the browser closes the existing connection to the 
web server, although parts of the response are still missing. When 
Tomcat send the next part of the response to the web server (e.G. Apache 
httpd), and the web server tries to send it back to the client 
(=browser), it detects a closed connection and this info message gets 
written into the log.

Depending on your load, the performance of the app and the patience of 
your users, a message every 20 to 30 seconds seems a bit to much.

You can add %D to your httpd access log, which will log microseconds 
response time to the access log, and also %{pid}P and %{tid}P, which 
will give the process id and the thread id of the thread serving the 
request. mod_jk also logs the process id and thread id automatically for 
each line, so there is a chance, that you can match those lines and find 
out, if they come from special requests (e.g. long running ones), from 
special users (IPs, Browsers) etc.

For the httpd access log configuration see

http://httpd.apache.org/docs/2.2/mod/mod_log_config.html

Caution: the timestamp in the jk log file, is the moment the problem got 
detected, the time stamp in the access log is the moment the request 
started (so you need to add the %d value to make them match).

Some more hints about your config included below.

Regards,

Rainer

Ingo Düppe wrote:
> Hello,
> 
> I found the following lines in my mod_jk.log every 20 to 30 seconds for 
> all of my instances.
> 
> [info] jk_ajp_common.c (1511): Writing to client aborted or client 
> network problems
> [info] jk_ajp_common.c (1996): (plexus12) request failed, because of 
> client write error without recovery in send loop attempt=0
> [info] jk_lb_worker.c (1092): unrecoverable error 200, request failed. 
> Client failed in the middle of request, we can't recover to another 
> instance.
> [info] mod_jk.c (2270): Aborting connection for worker=plexus
> 
> First I thought, this is caused because of some related network traffic 
> problem, but also the two Tomcat instances on the same machine appear in 
> the log.
> 
> My configuration exist of Windows 2003 SP2 Servers, Apache httpd 2.2.6, 
> mod_jk 1.2.25, and Tomcat 6.0.14.
> 
> 
> Please, can anybody tell me what's wrong with my configuration and what 
> is the meaning of these lines.
> 
> Thx in advanced
> 
> Ingo
> 
> 
> 
> My workers.properties:
> 
> workers.tomcat_home="C:\Server\tomcat-6.0.14"
> workers.java_home="c:\java\jdk-6.0"
> ps=\

The three above are not used since a long time. Remove them.

> worker.list=plexus,jkstatus
> worker.plexus11.port=8109
> worker.plexus11.host=openuss01
> worker.plexus11.type=ajp13
> worker.plexus11.lbfactor=10
> ...
> worker.plexus52.port=8209
> worker.plexus52.host=openuss05
> worker.plexus52.type=ajp13
> worker.plexus52.lbfactor=10
> 
> worker.jkstatus.type=status
> worker.plexus.type=lb
> worker.plexus.sticky_session=true
> worker.plexus.socket_timeout=20
> worker.plexus.reply_timeout=3000

3 seconds reply timeout sounds a bit ambitious (but I don't know what 
your app does)

> worker.plexus.max_reply_timeouts=40000

This max_reply_timeouts sounds a bit high. It controls after how many 
reply_timeouts a single sub worker of an lb gets put into an error state 
(and thus will not be used for a minute, before it gets tried again).

The counter gets incremented for each reply_timeout missed and gets 
divided by 2 about every minute. So assuming a steady flow of missed 
reply_timeouts, the value 40000 corresponds to about 20000 
reply_timeouts missed per minute.

> worker.plexus.balance_workers=plexus11,plexus21,plexus12,plexus22,plexus51,plexus31,plexus52


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