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From "Costas Stergiou" <cst...@aias.gr>
Subject Re: Re: mod_jk: ajp13: cpu load problem with apache
Date Thu, 09 May 2002 09:16:16 GMT
Hi Costin,
continuing on the problem:

1. I downloaded the latest code from CVS and compiled mod_jk.
2. Run apache with it and used gdb to get a stack trace upon
the problem. Here is the gdb output:

[helium]/#gdb httpd 24550
GNU gdb 5.0-aix43-010414
Copyright 2000 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "powerpc-ibm-aix4.3.3.0"...httpd: No such file or
dir
ectory.

//24550: No such file or directory.
Attaching to process 24550
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
---Type <return> to continue, or q <return> to quit---
[Switching to Thread 1]
0x20070e9c in jk_tcp_socket_recvfull ()
(gdb) bt
#0  0x20070e9c in jk_tcp_socket_recvfull ()
#1  0x2006b700 in ajp_connection_tcp_get_message ()
#2  0x200694c0 in ajp_get_reply ()
#3  0x20069344 in ajp_service ()
#4  0x200744c8 in jk_handler ()
#5  0x10020900 in ap_invoke_handler ()
#6  0x10044c30 in process_request_internal ()
#7  0x10045db4 in ap_process_request ()
#8  0x10002a50 in child_main ()
#9  0x1000244c in make_child ()
#10 0x10002140 in perform_idle_server_maintenance ()
#11 0x10001aec in standalone_main ()
#12 0x10001390 in main ()
#13 0x100001dc in __start ()
(gdb) quit
A debugging session is active.
Do you still want to close the debugger?(y or n) y
Detaching from program: , process 24550

The only way to stop the above is either by restarting apache or
killing the runaway apche process. gdb reports the same until I kill
the process (never gets out of that process).
Also, I must note that at the same time the jvm tomcat process also
consumes a lot of CPU untill I kill the httpd process.
Also, I use tomcat 4.0.3 with the compiled java mod_jk libs that
come with the distribution.

I hope that you can give some feedback on the above.
Also, I think that the above problem is occurring when I press
the stop button on my browser while I have made a 'big' request (one
that brings back a 'big' html page).

Any help is greatly welcome,
Thanks,
Costas



----- Original Message -----
From: <costinm@covalent.net>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
Sent: Thursday, May 02, 2002 7:57 PM
Subject: Re: Re: mod_jk: ajp13: cpu load problem with apache


> On Thu, 2 May 2002 csterg@aias.gr wrote:
>
> > First of all thank you for your interest.
> > I will download the latest code and try this out. I do have the debug
mode
> > enabled so I will sent you any errors (although I have not noticed
anything
> > special).
> > I don't think though that I can reproduce the problem myself.
> > About the gdb, I have no experience of how to attach to the process but
I will
> > do my best to find a colleague that does.
>
> Short course on gdb:
>
> ps -aux |grep httpd
> ( or ps -fea )
>
> Find the PID of the process that takes all the CPU, then
>
> gdb httpd PID
> and inside do a 'bt' ( backtrace ), it'll generate a stacktrace
> we can use.
>
>
> Costin
>
> > Thanks,
> > Costas
> > >
> > > Can you try the CVS head, and see if it still happens ?
> > > If so, can you give us more details that would allow to
> > > reproduce it ?
> > >
> > > Messages like 'it doesn't work for me, you figure out why'
> > > are not very helpfull.
> > >
> > > At least enable the debug messages, let it run until it
> > > hungs, then maybe trim the log and send the last entries.
> > > Or use gdb to attach to the problem process and do a
> > > stack trace.
> > >
> > > Costin
> > >
> > > On Wed, 1 May 2002, Costas Stergiou wrote:
> > >
> > > > Hi,
> > > > I have an installation of Apache 1.3.19 + Tomcat 4.0.3
> > > > on a aix4.3 machine with IBM JDK 1.3.0. I have two tomcat
> > > > engines and I use the lb worker of mod_jk to balance user
> > > > request to these two engines.
> > > >
> > > > The problem is that some httpd processes seem to go
> > > > into some cpu performance tasks and start consuming all
> > > > the cpu of the machine (2processors, 2GB mem). After
> > > > some time almost all available CPU is consumed by the
> > > > apache processes. If I kill the child processes that cause
> > > > the problem, the load falls back to normal. At the same time,
> > > > I notice that I have excessive CPU usage in one of the
> > > > tomcat instances.
> > > >
> > > > The problem keeps recurring all the time (almost every hour).
> > > > I read in the mail-archives about similar problems but I didn't
> > > > find a good answer.
> > > >
> > > > The version of mod_jk is the one in
jakarta-tomcat-connectors-4.0.2.01
> > > > I compiled the source on the same machine (aix).
> > > >
> > > > I have to say that I have noticed similar problems on many more
> > > > apache installations that have similar installations (apache, lb +
> > > > 2 or more tomcat engines) with older versions of mod_jk and tomcat.
> > > >
> > > > Actually, the above problem makes the lb worker unusable since
> > > > I cannot trust the setup in my production environment.
> > > >
> > > > Please, any idea or patches or whatever will be very helpful.
> > > > Thanks very much for any ideas,
> > > > Costas
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > > --
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> > >
> > >
> >
> >
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> >
> >
>
>
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