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Can I have multuple JVM in an application server .

Shyam Ramath
Greenhorn

Joined: Jun 24, 2005
Posts: 21
How many JVM can be started with in a Application server ? . Can I start a JVM with in a JVM ..

William Brogden
Author and all-around good cowpoke
Rancher

Joined: Mar 22, 2000
Posts: 12823
    
    5
Yes you can have multiple JVMs running in a single computer - why would you expect a problem?

Just like any other program you would have to watch out for conflicting use of resources - for example you can't have two Tomcat instances using the same ports.

Bill
Shyam Ramath
Greenhorn

Joined: Jun 24, 2005
Posts: 21
William Brogden wrote:Yes you can have multiple JVMs running in a single computer - why would you expect a problem?

Just like any other program you would have to watch out for conflicting use of resources - for example you can't have two Tomcat instances using the same ports.

Bill


In a tomcat I have a web application deployed , from that application can I start a JVM ?. ie to execute a job I need a separate JVM .
I know we can start a process which will be a separate JVM . A thread with in the tomcat JVM ( which may be costly operation ) .
Is there any JVM which allows a Virtual machine with in the same Virtual machine . Hope you are clear
Henry Wong
author
Sheriff

Joined: Sep 28, 2004
Posts: 18989
    
  40

Shyam Ramath wrote:In a tomcat I have a web application deployed , from that application can I start a JVM ?. ie to execute a job I need a separate JVM .
I know we can start a process which will be a separate JVM . A thread with in the tomcat JVM ( which may be costly operation ) .
Is there any JVM which allows a Virtual machine with in the same Virtual machine . Hope you are clear


I am assuming you mean virtualization like VmWare or Xen? Then no, the JVM doesn't do that level of virtualization.

Henry


Books: Java Threads, 3rd Edition, Jini in a Nutshell, and Java Gems (contributor)
William Brogden
Author and all-around good cowpoke
Rancher

Joined: Mar 22, 2000
Posts: 12823
    
    5
I know we can start a process which will be a separate JVM . A thread with in the tomcat JVM ( which may be costly operation ) .
Is there any JVM which allows a Virtual machine with in the same Virtual machine . Hope you are clear


There is little to be gained by starting a separate JVM because execution will still be limited by the CPU / memory / IO / etc of the host computer.

Unless your separate process requires a huge amount of memory, you might as well start this extra process as a Thread controlled by Tomcat. If there are other machines on your network which have free resources, Java has lots of ways to communicate with processes elsewhere on the network.

Bill
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Can I have multuple JVM in an application server .