Hi Rainer,

We're using the stock Apache 2.0 with RHEL4 on a x86 architecture. Obviously
I've built mod_jk from source.

Thanks for the detail - I'll see about adding the logs as you suggested.
The strange thing is that with 3 app servers it has been load balancing very
evenly for the last 10 months quite happily. Basically the introduction of
the 4th app server has changed the figures.

This is the thing that leads me to believe it could be a fault in the code -
literally I've changed nothing else about the app/configuration apart from
the extra lines in the workers.properties to add the 4th app server.

Rob

On 17/06/07, Rainer Jung <[EMAIL PROTECTED]> wrote:

Hi Rob,

at the moment there is no known problem with the balancing. I expect you
checked your mod_jk log file for errors.

What's your platform and what's your web server?

Since your request counts in the status display are still relatively
small, it looks like you get the unequal distribution pretty soon.
You've got no backend errors, so we could only speculate, if there are
few heavy weight sessions only hitting app101.

You could get a better impression about what's going on, by adding some
fields to you Apache LogFormat. See:

http://tomcat.apache.org/connectors-doc/reference/apache.html

There we have for example:

LogFormat "%h %l %u %t \"%r\" %>s %b \
%{JK_LB_FIRST_NAME}n %{JK_LB_LAST_NAME}n %{JK_LB_LAST_ACCESSED}n" \
extended

and then use "extended" as the name of the log format in your CustomLog
directive.

If you use Cookies for your sessions (and not URL encoded sessions), you
should also add %{JSESSIONID}C to the format, which will log the id of
the request. Finally you might like to add "%P %{tid}P" which shows the
pid and thread id of the apache process handling the request.

Those together help in finding out when and maybe why the balancing
mapped request unequally to the app servers.

If you need to post more exceprts from the status page, you could use
the additional parameters "mime=xml" (or =txt / ?prop) to get more mail
friendly formats.

Regards,

Rainer

Rob Kirkbride schrieb:
> Hi,
>
> We've added a 4th application server to our farm and since then I've
> noticed
> it's not load balancing equally across all our nodes at all.
>
> Each of the app servers has a lbfactor of 1 and we're using the default
> request strategy. I've copied the jkstatus page. I can see that app101
is
> handling around ten times as many requests as the other servers.
>
>  [E|R]  app101 ajp13 10.100.3.122:8009 10.100.3.122:8009 ACT OK   0 1 1
915
> 2033 0   1  1.7M 51M  0    9   app101       0/0
>   [E|R]  app102 ajp13 10.100.5.111:8009 10.100.5.111:8009 ACT OK   0 1 1
> 98  230  0   0  197K 5.8M 0    2   app102       0/0
>   [E|R]  app103 ajp13 10.100.5.113:8009 10.100.5.113:8009 ACT OK   0 1 1
> 101 227  0   0  187K 5.3M 0    3   app103       0/0
>   [E|R]  app104 ajp13 10.100.5.114:8009 10.100.5.114:8009 ACT OK   0 1 1
> 96  216  0   0  232K 1.1M 0    5   app104       0/0
>
> The app servers themselves seem quite happy so I'm not sure why it might
be
> doing this.
>
> Has anyone got any ideas - I don't particularly want to start changing
the
> balancing strategy/values on a live server without some though.
>
> Thanks,
>
> Rob Kirkbride
>

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