Multiple JVM instances

Dear all,
I am trying to create multiple JVM instances using createJavaVM(...) but I can't do it. When I try to create the second instance, the function returns an error.
Does anybody know about getting multiple JVM instances running??
Thanks in advance,

Hallo,
createJavaVM(...) trys to create a JVM in your current
process, so I am not surprised that you get an error
the second time round, because there is already a JVM
in the process. If you want multiple JVMs, each needs
to be in its own process.
Why do you want to create more than one JVM in your
process? The JVM is multithreadable, and you can start
more than one thread in the JVM. Would that do what
you want?I need multiple instances because my application needs nearly 2Gb of memory and the maximum heap I get is 1700 Mb. I think with multiple instances, I'll get it.
Do you know about getting a bigger heap??
>
David Singleton
[email protected]

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I have two mid tiers and both are load balanced by BigIP load balancer .
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Hello,
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regards
aseem

Each WL server runs in one JVM. If you want to have 4 JVMs, then run 4 WL
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"Aseem Rastogi" <[email protected]> wrote in message
news:[email protected]..
currently our App runs on 2 Iplanet App Server ( they are in Cluster)
and each App server has 2 VMs so we we are getting the feel of 4independent
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Michael Reiche wrote:
1) What is your requirement?
2) Clustering.
"Aseem Rastogi" <[email protected]> wrote in message
news:[email protected]..
Hi,
Is it possible to attach multiple JVMs to an instance of WLS6.1
so that all JVMs will be self sufficient in serving client
requests....
>>>
If it is possible then any pointers in that direction..???
regards
aseem

Load balancing HTTP requests for an OC4J instance w/multiple JVMs

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javanewbie80 wrote:
i am creating a singleton object. But singleton is per JVM (or rather per classloader) right? But i want to ensure only one instance of my singleton even if there are multiple jvms....how can i achieve that?You can't.
Given computers A and B. Neither have any connectivity by any means to the other.
Install the application on both and run it. There is no way for either application to know about the other thus only one of the following is possible.
1. Both applications run and create an instance. Then there are two instances and thus it fails.
2 The application refuses to run. Then there are none and thus it fails
Other solutions are possible given that some reasonable requirements based on actual business driven needs are presented.

Multiple JVMs within app server - refresh of metdata not working

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Steve.

I'd like to embed multiple instances of the JVM within
a single, multi-threaded native server process. I'm
aware this was not possible with the Sun JDK in the
past.
Is this still true (for JDK 1.4.1 say)?Yes, this is still true.
If it's still not possible, are there any timetables
as of when it might be available? No.
Likelihood?Check the current list of JSRs at http://www.jcp.org.
Ah, btw: Is support for VM unloading (during
DestroyJavaVM()) available now?No.
>
In any case: does anybody know of a JVM
implementation
available for Linux which supports multiple VM
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http://www.javagroup.org/echidna/
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Server, Multiple JVMs sources

Hi,
i've to create a (web serivce) server application. This application should be ready for clustering or something, if one server isn't fast enough.
I know already some things abou concurrency in Java. I'm no Java newbie. But i don't know how clustering works.
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Any good internet pages/PDFs which discusses this?
Any good books?
I really hope some can help me here, because it's very important for me.
Cheers,
Ingo

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Hi,
I am curious to know if one JDK spawning multiple JVM's cause any memory/performance issues. The reason being, my company is planning to have number of applications running in one Weblogic Server instance with Multiple JVM's spawning out of same JDK.
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Any help is greatly Appreciated.
Thanks

JDK installation is a just binary. There is not limit on creating number of JVM runtime process.
There should not be negative effect assuming you have enough capacity on hardware box.

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-XX:+UseConcMarkSweepGC
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Thx

The only other difference is the Heap size. 512mb for each JVM on the app server with multiple instances and 1GB for the server with 1 instance.This isn't a trivial difference. Basically you're saying "When I give the server 1 GB then it's okay but when I give it 512 MB it's not okay." If I saw those symptoms I would take them at face value to start with.
So, turn off one of those servers on the machine that has two. Don't change anything else. Testable prediction: That won't fix your problem.

Java client connecting to multiple weblogic instances

We have a standalone java client JMS application that needs to connect to multiple
Weblogic instances running in different domains.
The client works fine when we obtain an initial context to the multiple instances
without specifying a security principle and password. As soon as we add in this
information, we get problems: The initial context is still successfully retrieved
for each of the weblogic instances, but we cannot send JMS messages to destinations
on one of the Weblogic instances due to a security exception which states that
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Any advice would be appreciated.

You should first establish a trust relationship between your Weblogic
servers:
http://e-docs.bea.com/wls/docs70/secmanage/domain.html#1171534
It is very poorly documented since this is a change in the behavior with
previous versions and should have been in the Release Notes but instead
is inside the normal documentation.
--dejan
jonathan wrote:
Thanks Arvind, but both JVMs are the same (1.3.1) and there is no jsse stuff in
the classpath.
"Arvind Gudipati" <[email protected]> wrote:
check if yr client's jvm version is the same as server's jvm.. ive noticed
this problem a few times when i was using client jvm (1.4.x) connecting
to
server jvm (1.3.x).. also check if u have any jsse libraries in yr
classpath.. if so remove 'em
+arvind
"Jonathan" <[email protected]> wrote in message
news:3f2f9f19$[email protected]..
We have a standalone java client JMS application that needs to connect
to
multiple
Weblogic instances running in different domains.
The client works fine when we obtain an initial context to the multiple
instances
without specifying a security principle and password. As soon as we
add in
this
information, we get problems: The initial context is still successfully
retrieved
for each of the weblogic instances, but we cannot send JMS messages
to
destinations
on one of the Weblogic instances due to a security exception which
states
that
there is an 'Invalid Principal'.
Any advice would be appreciated.

Singletons across multiple JVMs

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Is there some way to do some of the initialization within these Singleton's just ONCE across the multiple instances of the JVM ie. a real Singleton across multiple JVMs?
Thanks
Ramdas

Pranav,
thanks for your suggestions.
the idea of using a Session bean to access a serialized object was one of my design options when i first implemented this, but then i decided against it because of the overhead of having to make an RMI call for every request to the 'running serial number'. The application being written is for a performance benchmark, and the request to the number being done at least once for every transaction, I chose to use Singletons.
It is a clustered EJB container(not like most conatiners), in the sense that a single container is spread across multiple JVMs.
Now if your application is getting clustured
then you have a problem, in that what you can do is
what object you have made put it in JNDI context and
everytime you want to edit it pull it out edit and set
it back. This will act a your singleton object in
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Ramdas

Single Process Multiple JVM

What are the possible ways of emboding multiple JVMs to a single java process.
Please post good articles if any. I have searched in google. But I couldnt get much. My requirement is to know how the heap ,stack, and inter JVM communication occures.
I have seen many applications like Quartz/OpenSymphony runs like multiple JVMs on single process.
thanks
Renjith.

Hi,
Declare the JavaVM *jvm instance as static... so u can get the jvm using JNI_GetCreatedJavaVMs during the next time

Multiple JVM instances

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