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From "Turner, John" <JTur...@AAS.com>
Subject RE: crontab problems
Date Tue, 25 Feb 2003 14:00:45 GMT

Agreed...using a Java program to watch Tomcat seems a little circular.
Plus, I don't see any sort of delay or "sleep" in the poster's JAva
code...it looks like it just keeps hammering at Tomcat, as the cron job is
"* * * * *".  Creating all those Runtime objects over and over can't be
helping performance any.

A simple shell script using wget would be fine...sure, you can watch the
output of "ps -ef", but that doesn't tell you if Tomcat is accepting
requests or not.  There could be an entry for Tomcat in the process table,
but Tomcat could be refusing requests.

I just write a simple JSP page that outputs the contents of a variable, like
"***SUCCESS***" or something like that, then use wget to grab that page
every so often and check for the string in the output...if it's there,
things should be OK (there are no guarantees).  If it's not, you have a
problem.  This way, the JSP page is compiled and cached by Tomcat, it uses
very little memory, and doesn't bog down the server.

There are plenty of other alternatives much more robust than a simple shell
script...you could use Netsaint/Nagios, Big Brother, and a whole bunch of
others.

John

> -----Original Message-----
> From: Hannes Schmidt [mailto:mail@schmidt-net.via.t-online.de]
> Sent: Tuesday, February 25, 2003 6:29 AM
> To: Tomcat Users List
> Subject: Re: crontab problems
> 
> 
> Right, you might also just put
> 
> JAVA_HOME=...
> 
> at the beginning of your crontab.
> 
> I assume you have good reasons to use a Java program to watch Tomcat.
> Personally, I would have written a shell script. If you 
> really want to use
> Java, you might want to use a different, more reliable 
> approach to detect
> (un)availability of Tomcat, something like
> 
> import java.net.*;
> URL url = new URL( "http://localhost:8080/examples" );
> URLConnection con = url.openConnection();
> con.setUseCaches( false );
> con.connect();
> if( con.getContentLength() > 0 ) {
>     // restart tomcat
> }
> 
> But I just wrote this out of my head ...
> 
> ----- Original Message -----
> From: "Ralph Einfeldt" <ralph.einfeldt@uptime-isc.de>
> To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
> Sent: Tuesday, February 25, 2003 10:43 AM
> Subject: RE: crontab problems
> 
> 
> You have to make shure that your script retstart_tomcat
> sets and exports all needed environment variables before
> calling ./startup.sh:
> 
> JAVA_HOME=/usr/local/java/jdk1.3.1
> CATALINA_HOME=<path to tomcat installation>
> CATALINA_BASE=<path to tomcat instance> or $CATALINA_HOME
> # JAVA_OPTS='-client -v'
> 
> export JAVA_HOME CATALINA_HOME CATALINA_BASE JAVA_OPTS
> ./startup.sh
> 
> > -----Original Message-----
> > From: Ayhan Peker [mailto:ayhan@image-data.com]
> > Sent: Tuesday, February 25, 2003 10:30 AM
> > To: tomcat-user@jakarta.apache.org
> > Subject: crontab problems
> >
> > but the last two lines returns
> > /////////////////////////
> > The JAVA_HOME environment variable is not defined
> > message..
> > /////////////////////////
> > my retstart_tomcat scrip is
> > #!/bin/sh
> > cd /usr/local/tomcat/bin
> > ./startup.sh
> 
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