So I tested again and it looks like Jboss accepts new connection when
it already undeployed the service. Do you have any advice of how I can
handle this scenario. I need to cleanly take that node out of service
from mod_jk with no customer impact. Is there anyway in apache to do
that so that it detects below scenario ..any possible way? Thanks for
your help.
I see the following of http code 503:
<html><head><title>JBossWeb/2.0.0.GA_CP01 - Error
report</title><style><!--H1
{font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:22px;}
H2
{font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:16px;}
H3
{font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:14px;}
BODY {font-family:Tahoma,Arial,sans-serif;color:black;background-color:white;}
B {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;}
P
{font-family:Tahoma,Arial,sans-serif;background:white;color:black;font-size:12px;}A
{color : black;}A.name {color : black;}HR {color :
#525D76;}--></style> </head><body><h1>HTTP Status 503 - This
application is not currently available</h1><HR size="1"
noshade="noshade"><p><b>type</b> Status report</p><p><b>message</b>
<u>This application is not currently
available</u></p><p><b>description</b> <u>The requested service (This
application is not currently available) is not currently
available.</u></p><HR size="1"
noshade="noshade"><h3>JBossWeb/2.0.0.GA_CP01</h3></body></html>
On Mon, Mar 2, 2009 at 5:01 PM, Rainer Jung <rainer.j...@kippdata.de> wrote:
> On 03.03.2009 01:45, Mohit Anchlia wrote:
>>
>> Is there a way to configure ping in workers.properties to also check
>> for 503 in addition to cping/cpong? I am sure you are going to laugh
>> at me.
>
> No I'm not laughing, but as I wrote, at the time Tomcat returns the cpong,
> there is no http status. There isn't yet a request.
>
> So this feature doesn't make sense.
>
> Regards,
>
> Rainer
>
>> On Mon, Mar 2, 2009 at 1:26 PM, Rainer Jung<rainer.j...@kippdata.de>
>> wrote:
>>>
>>> On 02.03.2009 20:28, Mohit Anchlia wrote:
>>>>
>>>> I will change the JkLogLevel and post the results. I have a question
>>>> though: Does prepost_timeout also detect if it received http code such
>>>> as 503 from app server.
>>>
>>> prepost_timeout activates Cping/Cpong before each request. mod_jk will
>>> send
>>> a tiny test packet to the ap server before each request, and the AJP
>>> protocol stack of the app server will immediately respond with a tiny
>>> reply
>>> packet, indicating that it is still alive and able to parse AJP messages.
>>> The web application itself is not involved in this part of the
>>> processing,
>>> neither is any http request or response (or their AJP equivalent).
>>>
>>> So prepose_timeout will detect, if it receives some garbage (anything
>>> different from a Cpong packet), but http responses with http status codes
>>> are only generated much later and will thus not influence the prepose
>>> Cping/Cpong result.
>>>
>>> See also:
>>>
>>> http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html
>>>
>>> Regards,
>>>
>>> Rainer
>>>
>>>> On Wed, Feb 25, 2009 at 9:05 AM, Rainer Jung<rainer.j...@kippdata.de>
>>>> wrote:
>>>>>
>>>>> On 25.02.2009 17:10, Mohit Anchlia wrote:
>>>>>>
>>>>>> you are right there is a mod-jk.conf. So given my workers.properties
>>>>>> file what should I change so that mod_jk detects that app server is
>>>>>> down before attempting to send the request. Shouldn't "retries" in
>>>>>> workers.properties try to connect to some other app server instead.
>>>>>
>>>>> Just a wild guess: your prepost timeout of 5 milliseconds produces the
>>>>> error
>>>>> messages you cited. First correct this timeout, then do another clean
>>>>> test
>>>>> on your test system. You can even increase JkLogLevel to trace (not in
>>>>> production) so we can see exactly what is going on. Do not send many
>>>>> requests with JkLogLevel trace, just do a minimal test that shows the
>>>>> problem.
>>>>>
>>>>> The early detection of a broken instance should be possible with your
>>>>> configuration.
>>>>>
>>>>>> Here is mod-jk.conf
>>>>>>
>>>>>> # Where to find workers.properties
>>>>>> JkWorkersFile conf/workers.properties
>>>>>>
>>>>>> # Where to put jk logs
>>>>>> JkLogFile /var/log/apache2/mod_jk.log
>>>>>>
>>>>>> # Set the jk log level [debug/error/info]
>>>>>> JkLogLevel error
>>>>>>
>>>>>> # Allow mod_jk worker status reports, with the URL of
>>>>>> http://servername/JkStatus
>>>>>> ## This is very helpful for monitoring purposes, but should be
>>>>>> ## allowed from the local machine.
>>>>>> <Location /JkStatus>
>>>>>> Order deny,allow
>>>>>> Deny from all
>>>>>> Allow from localhost
>>>>>> </Location>
>>>>>>
>>>>>> #JkMount /JkStatus status
>>>>>>
>>>>>> # Below line forward all requests to application server
>>>>>> #JkMount /* local
>>>>>>
>>>>>>
>>>>>> On Wed, Feb 25, 2009 at 2:55 AM, Rainer Jung<rainer.j...@kippdata.de>
>>>>>> wrote:
>>>>>>>
>>>>>>> On 25.02.2009 02:47, Mohit Anchlia wrote:
>>>>>>>>
>>>>>>>> In httpd conf I just see JkMount and no other directive. I searched
>>>>>>>> for
>>>>>>>> Jk.
>>>>>>>
>>>>>>> There should be others as well, for instance JkWorkersFile to point
>>>>>>> to
>>>>>>> your
>>>>>>> workers.properties. The names of the directives are case insensitive,
>>>>>>> they
>>>>>>> can also be in files included to your main httpd configuration file
>>>>>>> via
>>>>>>> include directives.
>>>>>>>
>>>>>>>> Here is workers.properties file:
>>>>>>>
>>>>>>> ...
>>>>>>>>
>>>>>>>> # appfe1
>>>>>>>
>>>>>>> ...
>>>>>>>>
>>>>>>>> worker.appfe1.socket_timeout=5
>>>>>>>
>>>>>>> I generally don't like socket_timeout. Others do :)
>>>>>>>
>>>>>>>> worker.appfe1.prepost_timeout=5
>>>>>>>
>>>>>>> 5 milliseconds prepost timeout? You're kidding. I assume it should
>>>>>>> have
>>>>>>> been
>>>>>>> 5000.
>>>>>>>
>>>>>>>> worker.appfe1.recycle_timeout=900
>>>>>>>
>>>>>>> This is deprecated. Use connection_pool_timeout instead. The value is
>>>>>>> OK,
>>>>>>> you should set connectionTimeout on the Tomcat AJP connector to
>>>>>>> 900000
>>>>>>> then.
>>>>>>>
>>>>>>> Since you are using prefork MPM, you might want to set
>>>>>>> connection_pool_minsize to 0 if you want to keep the number of
>>>>>>> established
>>>>>>> connections low.
>>>>>>>
>>>>>>> And the same for the other members of the load balancer.
>>>>>>>
>>>>>>>> On Tue, Feb 24, 2009 at 4:50 PM, Rainer
>>>>>>>> Jung<rainer.j...@kippdata.de>
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> On 25.02.2009 00:00, Mohit Anchlia wrote:
>>>>>>>>>>
>>>>>>>>>> Reposting:
>>>>>>>>>>
>>>>>>>>>> Apache Server - 2.2
>>>>>>>>>> Tomcat server 6
>>>>>>>>>> Jboss - 4.2
>>>>>>>>>>
>>>>>>>>>> We have Web Servers talking to Jboss App Servers over mod_jk. When
>>>>>>>>>> we
>>>>>>>>>> do our patch or upgrade of software we do it in rolling fashion so
>>>>>>>>>> that there is "0" customer impact. But it looks like mod_jk load
>>>>>>>>>> balancer on Web server doesn't detect it as soon as Jboss App
>>>>>>>>>> Server
>>>>>>>>>> goes down. Our goal is to have 0 customer impact. So my question
>>>>>>>>>> is
>>>>>>>>>> what can we do to overcome this problem. Web Server sees Http
>>>>>>>>>> Error
>>>>>>>>>> Code 503.
>>>>>>>>>>
>>>>>>>>>> Information from log file:
>>>>>>>>>>
>>>>>>>>>> [Mon Feb 23 13:39:42.146 2009] [31682:4143745888] [error]
>>>>>>>>>> ajp_connection_tcp_get_message::jk_ajp_common.c (966): (appfe4)
>>>>>>>>>> can't
>>>>>>>>>> receive the response message from tomcat, network problems or
>>>>>>>>>> tomcat
>>>>>>>>>> (10.10.81.89:8009) is down (errno=104)
>>>>>>>>>> [Mon Feb 23 13:39:42.147 2009] [31682:4143745888] [error]
>>>>>>>>>> ajp_service::jk_ajp_common.c (2097): (appfe4) Connecting to tomcat
>>>>>>>>>> failed. Tomcat is probably not started or is listening on the
>>>>>>>>>> wrong
>>>>>>>>>> port
>>>>>>>>>
>>>>>>>>> This means that mod_jk detected that your backend is down and thus
>>>>>>>>> puts
>>>>>>>>> it
>>>>>>>>> into an error state. All following requests will no longer be sent
>>>>>>>>> to
>>>>>>>>> this
>>>>>>>>> backend. Once a minute it will send a request there and try, but as
>>>>>>>>> long
>>>>>>>>> as
>>>>>>>>> it is down this test will not succeed and thus all requests will be
>>>>>>>>> sent
>>>>>>>>> to
>>>>>>>>> other nodes.
>>>>>>>>>
>>>>>>>>> The first request that gets sent to the backend you stopped might
>>>>>>>>> get
>>>>>>>>> an
>>>>>>>>> error back. If you want to prevent that from happening, use
>>>>>>>>> Cping/Cpong:
>>>>>>>>>
>>>>>>>>> http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html
>>>>>>>>>
>>>>>>>>> so we will detect the broken node before actually sending a request
>>>>>>>>> there.
>>>>>>>>> More details are not possible to give without your JK configuration
>>>>>>>>> (Jk
>>>>>>>>> directive sin httpd configuration files, workers.properties and if
>>>>>>>>> used
>>>>>>>>> uriworkermap.properties).
>>>>>>>>>
>>>>>>>>> The line number of the above message tells me you are using mod_jk
>>>>>>>>> 1.2.25.
>>>>>>>>> Although there's nothing wrong in principal with 1.2.25, we always
>>>>>>>>> try
>>>>>>>>> to
>>>>>>>>> improve and you might consider switching to 1.2.27.
>>>>>>>>>
>>>>>>>>> You should also increase your JkLogLevel to info. As long as only
>>>>>>>>> occasional
>>>>>>>>> info messages are in your log file everything is fine, but once
>>>>>>>>> error
>>>>>>>>> messages show up, the additional info messages contain useful
>>>>>>>>> formation.
>
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