Re: mod_jk hangs

Wed, 05 May 2004 09:21:02 -0700

Okay, here is the section from our server.xml in production:

  <Service name="Catalina">
    <Connector port="8080" />

    <!-- This is here for compatibility only, not required -->
    <Connector port="8090" protocol="AJP/1.3" />

    <Engine name="Catalina" defaultHost="localhost" jvmRoute="ajp13_0">
      <Logger className="org.apache.catalina.logger.FileLogger" />

      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
             resourceName="UserDatabase" />

      <Host name="localhost" appBase="webapps" />
    </Engine>
  </Service>

I thought it interesting the comment that "this is here for compatibility only, not required." It sounds to me that connector is required if I want AJP/1.3 isn't it? I can't remember if that comment was there or if I (mistakingly) added it. Anyways, I see that I could probably do well to add the minSpareThreads and maxSpareThreads parameters. Any idea where I should look in my httpd.conf file to see what values to set these to?

Thanks,
-shawn

Randall Svancara wrote:

You might want to check to make sure you have enough tomcat threads for
each apache thread.

I usually give tomcat a few more threads than apache just to make sure I
do not run out.

-------snip----------------

<!-- Define a Coyote/JK2 AJP 1.3 Connector on port 8009 -->
<Connector port="8009" enableLookups="false" redirectPort="8443" debug="0"
minSpareThreads="100" maxSpareThreads="300"
protocol="AJP/1.3" />
-------snip----------------

So you might want to increase min and max spare threads to accomodate
more requestes from apache to tomcat via mod_jk.

Randall 



-----Original Message-----
From: Shawn Wilson [mailto:[EMAIL PROTECTED]
Sent: Wednesday, May 05, 2004 9:50 AM
To: [EMAIL PROTECTED]
Subject: mod_jk hangs


Just yesterday we started running into problems requesting pages on our production website through mod_jk. Previously everything had been working fine for months. Essentially what happens is when you request the page for the first time (doesn't seem to matter what browser you're using) the browser just sits and spins. Then after hitting refresh (Ctrl+R) a couple times it finally comes up. Subsequent visits to the same page continue to work for me in Mozilla but after closing IE and reopening it after a couple more requests it hangs again. In case it helps, the site in question is http://www.atmreports.com.

I simply cannot figure out what is going on. I do see many errors in the

mod_jk.log, but these had been there before when everything worked fine
too:

[Wed May 05 09:27:46 2004] [jk_ajp_common.c (1137)]: Error reading reply from tomcat. Tomcat is down or network problems.
[Wed May 05 09:27:46 2004] [jk_ajp_common.c (1290)]: ERROR: Receiving from tomcat failed, recoverable operation. err=0
[Wed May 05 09:27:46 2004] [jk_ajp_common.c (1309)]: sending request to

tomcat failed in send loop. err=0
[Wed May 05 09:27:46 2004] [jk_ajp_common.c (738)]: ERROR: can't receive the response message from tomcat, network problems or tomcat is down. err=-1

A few things to note, any of which may contribute to the problem but for

the life of me I can't figure out how:

1. On Friday we just moved out datacenter to a new location. However we see this problem even internally at the location so I don't believe it is any sort of routing issue (and the problem didn't start until
Tuesday).

2. The clock on this webserver was many hours off. On Tuesday (yes, the day the problems started) the clock was synchronized and the timezone correctly set so the machine now has correct time. This seems to be the most probable cause simply because it happened around the same time, but

I just can't understand why or how.

3. Yesterday we rebooted the box to see if that would help. It did. We didn't have any more problems at all that day until this morning we see the problems again. Today we recycled just tomcat and that seems to have

fixed it as well, though I expect that by tomorrow I will see the problem again.

4. I wouldn't think this could have anything to do with that new Sasser worm, but listing that just in case.

The machine is running Linux kernel 2.4.20-8 with httpd-2.0.40-21 and jakarta-tomcat-5.0.18. We are running 4 instances of tomcat on the box, each started with the following JVM options:

-Xmn128M -Xmx1024M -Djava.awt.headless=true

Nothing having to do with configuration has changed at all in a long time. Here is the relevant configuration sections:


# Mod_jk (Tomcat connector)
LoadModule jk_module modules/mod_jk.so

<IfModule mod_jk.c>
     JkWorkersFile /etc/httpd/conf/workers.properties
     JkLogFile /var/log/httpd/mod_jk.log
     JkLogLevel info
     JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
     JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories
     JkRequestLogFormat "%w %V %T"
</IfModule>

...and later (in a <VirtualHost> section)...

     JKMount /myreports balancer
     JKMount /myreports/* balancer

Here is our workers.properties file (comments removed):

workers.java_home=/usr/java/j2sdk1.4.2_03
ps=/
worker.list=balancer

worker.ajp13_0.port=8090
worker.ajp13_0.host=localhost
worker.ajp13_0.type=ajp13
worker.ajp13_0.lbfactor=1

worker.ajp13_1.port=8091
worker.ajp13_1.host=localhost
worker.ajp13_1.type=ajp13
worker.ajp13_1.lbfactor=1

worker.ajp13_2.port=8092
worker.ajp13_2.host=localhost
worker.ajp13_2.type=ajp13
worker.ajp13_2.lbfactor=1

worker.ajp13_3.port=8093
worker.ajp13_3.host=localhost
worker.ajp13_3.type=ajp13
worker.ajp13_3.lbfactor=1

worker.balancer.type=lb
worker.balancer.balanced_workers=ajp13_0, ajp13_1, ajp13_2, ajp13_3
worker.balancer.sticky_session=1


Any help would be greatly appreciated!

Thanks,
-shawn


--
====================================
Shawn Wilson [EMAIL PROTECTED]
Software Developer, ATMReports.com
PH: 877-327-0873, FAX: 406-294-5806
====================================

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature

Reply via email to