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From "Michael Locasto" <mloca...@pfsmarketing.com>
Subject Re: Tomcat + James in a single jvm process
Date Tue, 04 Jun 2002 14:48:43 GMT

While it is true that starting and running a single JVM instance is less
expensive (mostly in terms of memory)
than starting and running two or more JVMs on the same processor/box,
there are several good reasons for
keeping Tomcat and James running in separate JVMs. Trying to avoid the
"overhead" of two JVMs really
doesn't gain you anything significant. What is more critical is the work
done inside the two threads (James,Tomcat).

Heap size is a concern. JVMs have a limit on the amount of memory they use
by default. You can run the JVM with a -server
option, which AFAIK increases that limit. However, depending on your load,
having both Tomcat and James in the same JVM may cause you to run
into a shortage of resources within the JVM, even though you may have
saved on memory outside the JVM.

Second, you are putting all your eggs in one basket (sorry for the idiom).
Putting both Tomcat and James in the same JVM
is not a fault-tolerant solution. If the JVM crashes, you lose both your
servers. If your clients have a two processor machine,
or two boxes, keeping them separate will provide you and them with a more
scaleable solution.

Third, it should be relatively simple for you to write a custom
start/build script that runs both Tomcat and James. In this way, it
still "looks" like you are starting a single process, but inside the
script you start 2 JVMs (or call the Tomcat startup script and the James
startup script). That approach is much easier than trying to tie the two
binaries together or compile a custom version.

If you are looking for tutorials for Tomcat, the documentation within the
Tomcat distributions and on the tomcat website is
very good. http://jakarta.apache.org/tomcat/  The default configuration
for the Tomcat distribution runs with minimal changes.
Of course, what JSP/webapps you put in from there is another story ;) The
tomcat-users mailing list should be fairly helpful along with the docs.
I hope this has been helpful.


----- Original Message -----
From: "mohan narayanaswamy" <mohandb2@yahoo.co.uk>
To: "James Developers List" <james-dev@jakarta.apache.org>
Sent: Tuesday, June 04, 2002 7:02 AM
Subject: RE: Tomcat + James in a single jvm process

> single JVM process will reduce the overload.
> u will be required less cpu,memory and moreover
> efficient when compared to two process server.

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