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From André Warnier ...@ice-sa.com>
Subject Re: And how about this mod_jk.log ?
Date Mon, 02 Feb 2009 22:44:24 GMT
Hi.

Just to anyone who contributed ideas to the issue originally mentioned, 
thanks.

As a reminder, the problem was, on the one hand, entries like this one 
in the mod_jk logfile :

[Mon Jan 19 15:02:52 2009] [6802:4416] [info] 
ajp_process_callback::jk_ajp_common.c (1447): Writing to client aborted 
or client network problems
[Mon Jan 19 15:02:52 2009] [6802:4416] [info] 
ajp_service::jk_ajp_common.c (1846): (ajp13) request failed, because of 
client write error without recovery in send loop attempt=0
[Mon Jan 19 15:02:52 2009] [6802:4416] [info]  jk_handler::mod_jk.c 
(2190): Aborting connection for worker=ajp13

and on the other hand user's Internet Explorer displaying a not very 
helpful internal error page saying "This page cannot be displayed".

It turned out that what looked at first (to the customer) like a server 
or application problem, was in reality an intermediate network problem, 
with some in-between piece of equipment cutting off the browser/server 
TCP connection before the server had a chance to send the response
(and, thus, that the mod_jk log was very accurate).

Because the first part of this test had to be done by a non-specialist 
customer on a workstation to which I did not have access, I ended up 
writing a simple Perl script based on the integral LWP module, to better 
trace the problem at the workstation level.
The script is not very sophisticated, but was enough to demonstrate the 
problem and create a time-stamped trace allowing it to be cross-checked 
with the mod_jk log.  The script is very easy to use, on any platform 
that has perl installed (and that nowadays is not difficult to achieve, 
not intrusive, and easily cleaned up afterward if you so wish).  It 
works a bit like a URL -checker, but has some options better-adapted to 
what I needed.
You just feed it a text file containing some HTTP/HTTPS URLs to use for 
testing, and it will print useful time-stamped messages to STDOUT. It 
only gets verbose in case of error, which is generally what one wants.

You can download it from here, and feel free to use it and modify it as 
you please, under whichever free license you favor.

http://dev.dev.wissensbank.com/public/HTTPchecker.pl

"perl HTTPchecker.pl" will display the usage.

Also, if by any chance you did not know this much more sophisticated 
tool which comes automatically with the perl distributions, check out 
"lwp-request".

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