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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
CATALINA_OPTS v JAVA_OPTS - What is the difference?

There are two environment variables - CATALINA_OPTS and JAVA_OPTS - which are both used in the catalina.sh startup and shutdown script for Tomcat. They are described in comments within that file as:
(optional) Java runtime options used when the "start", "stop" or "run" command is executed [JAVA_OPTS]
and
(optional) Java runtime options used when the "start" or "run" command is executed [CATALINA_OPTS]

So why are there two different variables? And what's the difference?

Firstly, anything specified in EITHER variable is passed, identically, to the command that starts up Tomcat - the "start" or "run" command - but only values set in JAVA_OPTS are passed to the "stop" command. That probably doesn't make any difference to how Tomcat runs in practise as it only effects the end of a run, not the start.

The second difference is more subtle. Other applications may also use JAVA_OPTS, but only Tomcat will use CATALINA_OPTS. So if you're setting environment variables for use only by Tomcat, you'll be best advised to use CATALINA_OPTS, whereas if you're setting environment variables to be used by other java applications as well, such as by JBoss, you should put your settings in JAVA_OPTS.




"OK - so that's the difference. Give me some examples of what can go in there!"

You can increase heap memory available to the JVM - see here

You can open remote monitoring ports so that Jconsole on another system can watch how your Tomcat is running - see here

You can add in a -server to switch from the client (quicker start, slower running) JVM to the server (slower starting, quicker running) JVM.

You can increase java thread stack size using the -Xss option (same way to specify amount of memory as in -Xms and -Xmx as described in the "increase heap memory" link above.
(written 2009-05-09)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
A654 - Web Application Deployment - Configuring and Controlling Tomcat
  [837] Tomcat - Shutdown port - (2006-08-18)
  [907] Browser -> httpd -> Tomcat -> MySQL. Restarting. - (2006-10-28)
  [914] A practical example of roles - (2006-11-04)
  [1351] Compressing web pages sent out from server. Is it worth it? - (2007-09-14)
  [1370] Apache Tomcat Performance Tuning - (2007-09-29)
  [1503] Web page (http) error status 405 - (2008-01-12)
  [1553] Automatic startup and shutdown of Tomcat - (2008-02-24)
  [1762] WEB-INF (Tomcat) and .htaccess (httpd) - (2008-08-20)
  [1943] Port and Glasses - (2008-12-14)
  [1994] tomcat-users.xml; what a difference a space made - (2009-01-16)
  [2039] The Invoker - (2009-02-13)
  [2061] Tomcat 6 - Annotated Sample Configuration Files - (2009-03-01)
  [2652] Reading and writing cookies in Java Servlets and JSPs - (2010-02-26)
  [3043] Gathering information - logging - with log4j. First steps. - (2010-11-12)


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Crossrefering documents with uniqueness and inconsistency issues - PHP proof of concept demo
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Updating my public profile - Graham Ellis
CATALINA_OPTS v JAVA_OPTS - What is the difference?
Admins thoughts on banning a member from a forum
Get it right ... if it goes wrong, it takes so much effort to sort out!
PHP - getclass v instanceof
A long day to guess where
On the roof of a Melksham Spa House
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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