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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: 12760
    
    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: 18509
    
  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: 12760
    
    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
 
 
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