Reloading w/ Manager on cluster?

2002-10-10 Thread Ben Ricker

I have a setup with 2 APache servers (1.3.27 on Redhat 7.3) talking to 4
tomcats clustered across two SOlaris 8 boxes running Tomcat 4.0.5. We
have a load balancer across the web servers and, of course, mod_jk 1.2.0
doing the load balancing across the Tomcats.

We have a QA environment where I want the abilty to reload the apps
through the manager application. We cannot do it through the Apache load
balancer because you cannot quarantee what Tomcat you are going to talk
to at any given request.

I thought of having Tomcat use its embedded web server on 8080 and 8081
on each Tomcat server and have the developers call those for reloading,
but they would have to do that 4 times for every reload. Plus, if we
scale to a bigger cluster, the problem becomes worse.

I do have a script that stops and restarts all of the tomcats from a
central location, but is there any danger to be restarting Tomcat
frequently? Has anyone worked around a cluster for the management app?

Thanks,

Ben

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Ben Ricker [EMAIL PROTECTED]
Wellinx.com


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RE: Reloading w/ Manager on cluster?

2002-10-10 Thread Michael Schulz

I am facing a similar issue in terms of updating our tomcat servers in the
cluster.

I was thinking about doing a similar thing...using the http connector (which
is behind a firewall and not accessible to the outside world) on each tomcat
server to communicate with the tomcat manager app
(http://tomcat1:8080/manager/reload?path=/mywebapp).  I would think it would
be easy enough to write a script that uses Lynx to invoke this same URL on
all four servers.  I don't think it is a problem to be restarting tomcat
frequently, at least I have not seen a problem and we've done this quite a
bit in our QA environment.

Ben, may I see the script that you are currently using to restart tomcat on
the multiple servers?  Also, have you done any load testing? If so, what
sort of load is your system able to support?

-Mike Schulz


-Original Message-
From: Ben Ricker [mailto:[EMAIL PROTECTED]]
Sent: Thursday, October 10, 2002 1:32 PM
To: [EMAIL PROTECTED]
Subject: Reloading w/ Manager on cluster?


I have a setup with 2 APache servers (1.3.27 on Redhat 7.3) talking to 4
tomcats clustered across two SOlaris 8 boxes running Tomcat 4.0.5. We
have a load balancer across the web servers and, of course, mod_jk 1.2.0
doing the load balancing across the Tomcats.

We have a QA environment where I want the abilty to reload the apps
through the manager application. We cannot do it through the Apache load
balancer because you cannot quarantee what Tomcat you are going to talk
to at any given request.

I thought of having Tomcat use its embedded web server on 8080 and 8081
on each Tomcat server and have the developers call those for reloading,
but they would have to do that 4 times for every reload. Plus, if we
scale to a bigger cluster, the problem becomes worse.

I do have a script that stops and restarts all of the tomcats from a
central location, but is there any danger to be restarting Tomcat
frequently? Has anyone worked around a cluster for the management app?

Thanks,

Ben

--
Ben Ricker [EMAIL PROTECTED]
Wellinx.com


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RE: Reloading w/ Manager on cluster?

2002-10-10 Thread Ben Ricker

The script is rather rough right now, but it is simple. I use ssh to
call the tomcat startup script like so:

ssh hostname /etc/init.d/tomcat stop

Here is the contents of the startup script. I have two Tomcat
directories, /usr/local/tomcat1 and /usr/local/tomcat2. I have them
sharing a centralized webapps directory in /usr/local/webapps. I run the
tomcat processes with an unpriveledged use, 'tomcat'.

HTH,

Ben Ricker

-Tomcat Startup Script---

#!/bin/sh
#
# tomcatStarts the Tomcat server
#
# Author:   All kinds of people
#
# chkconfig: 345 50 50
#
# processname: httpd
# pidfile: /usr/local/apache/logs/httpd.pid

# Begin /etc/init.d/apache

case $1 in
  start)
echo -n Starting Tomcat...
/bin/su tomcat -c /usr/local/tomcat1/bin/startup.sh
/bin/su tomcat -c /usr/local/tomcat2/bin/startup.sh
;;

  stop)
echo -n Stopping Tomcat...
/bin/su tomcat -c /usr/local/tomcat1/bin/shutdown.sh
/bin/su tomcat -c /usr/local/tomcat2/bin/shutdown.sh
;;

  restart)
echo -n Restarting Tomcat...
/bin/su tomcat -c /usr/local/tomcat1/bin/shutdown.sh
/bin/su tomcat -c /usr/local/tomcat2/bin/shutdown.sh
sleep 5
/bin/su tomcat -c /usr/local/tomcat1/bin/startup.sh
/bin/su tomcat -c /usr/local/tomcat2/bin/startup.sh
;;

  *)
echo Usage: $0 {start|stop|restart}
;;

esac

# End /etc/init.d/tomcat


On Thu, 2002-10-10 at 13:52, Michael Schulz wrote:
 I am facing a similar issue in terms of updating our tomcat servers in the
 cluster.
 
 I was thinking about doing a similar thing...using the http connector (which
 is behind a firewall and not accessible to the outside world) on each tomcat
 server to communicate with the tomcat manager app
 (http://tomcat1:8080/manager/reload?path=/mywebapp).  I would think it would
 be easy enough to write a script that uses Lynx to invoke this same URL on
 all four servers.  I don't think it is a problem to be restarting tomcat
 frequently, at least I have not seen a problem and we've done this quite a
 bit in our QA environment.
 
 Ben, may I see the script that you are currently using to restart tomcat on
 the multiple servers?  Also, have you done any load testing? If so, what
 sort of load is your system able to support?
 
 -Mike Schulz
 
 
 -Original Message-
 From: Ben Ricker [mailto:[EMAIL PROTECTED]]
 Sent: Thursday, October 10, 2002 1:32 PM
 To: [EMAIL PROTECTED]
 Subject: Reloading w/ Manager on cluster?
 
 
 I have a setup with 2 APache servers (1.3.27 on Redhat 7.3) talking to 4
 tomcats clustered across two SOlaris 8 boxes running Tomcat 4.0.5. We
 have a load balancer across the web servers and, of course, mod_jk 1.2.0
 doing the load balancing across the Tomcats.
 
 We have a QA environment where I want the abilty to reload the apps
 through the manager application. We cannot do it through the Apache load
 balancer because you cannot quarantee what Tomcat you are going to talk
 to at any given request.
 
 I thought of having Tomcat use its embedded web server on 8080 and 8081
 on each Tomcat server and have the developers call those for reloading,
 but they would have to do that 4 times for every reload. Plus, if we
 scale to a bigger cluster, the problem becomes worse.
 
 I do have a script that stops and restarts all of the tomcats from a
 central location, but is there any danger to be restarting Tomcat
 frequently? Has anyone worked around a cluster for the management app?
 
 Thanks,
 
 Ben
 
 --
 Ben Ricker [EMAIL PROTECTED]
 Wellinx.com
 
 
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 mailto:[EMAIL PROTECTED]
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Wellinx.com


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