Multiple JVM instances and host computer performance

Hi,
I was wondering if anyone has any facts or sources about how running multiple JVM instances impacts the performance of the hosting computer ?
For example, say you have a long running server process that creates a JVM, how is the performance of the computer impacted if there are five of those processes running, versus ten versus ...
This is a very "it depends" question, but I would like to get an idea of the baseline performance impact that comes with running a JVM, and if there is anyone here that has experience running multiple JVMs I'd appreciate any feedback, whether it's "don't do it, ever" or "no problem!"
Thanks

My only experience with multiple VMs is when I have several Java GUI apps (eclipse, jedit, dbvisualizer) plus tomcat and maybe an ant running on XP.
I don't think that the existence of multiple VMs is in and of itself a problems, but JVMs do tend to be fairly memory hungry, so if you don't have a lot of RAM, you may find yourself crawling along as swapping heats up.
I think that later versions of the Windows VM have started to take advantage of sharing certain core libraries, or pieces of them, so that you don't have as big an incremental memory footprint for additional VMs. I don't know which versions or how much this actually reduces the foot print of second and subsequent VMs though.

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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]

Multiple jvm/instances/auto restart

Hi
I have two mid tiers and both are load balanced by BigIP load balancer .
I want to know the following
1. How can I increase the jvm process and what is it's advantages/disadvantages ?
2. Is it possible to set automatic restart feature in the Application server ?
3. In some article I found that we can create multiple oc4j instance and give the same
context root . What is the advantages/disadvantages ?
4. Is there any feature in the app sever for monitoring like if the appserver uses more resources or crashes we can send email to the administrator ?
Thanks,
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Hello,
My answer is based on the fact that you are using OracleAS 10g (R1, 2 or 3) -which one are you using?-
OPMN: Oracle Process Management and Notification is the service in charge of starting and monitor the status of a process such as OC4J and its related JVM. Take a look to the OPMN documentation of your release. (and Administration Guide)
To have multiple OC4J that use the same context root (same application deployed) you need to have an instance with cluster enabled for several process of the same instance. Take a look to the deployment and configuration guide of your App server version.
OPMN, Clustering, and Oracle Deployment guides will answer the 4 questions you have.
Regards
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Multiple JVm instances error in iplanet 4.1

the error message is :
info ( 1184): JVM instance has already been created within the process, numVMs=1
I have an NSAPI filter which uses JNI and will create an individual JavaVM.
I understand in the process no more than 1 JavaVM shall be initialized yet I can't find a way to attach my NSAPI filter to the JavaVM created by the iplanet server.
Does anybody has any idea how to solve this?

Thanks for your reply. It seems odd though that IWS 4.1 seems to work fine w/sdk1.4.1 on my WinNT machine???

Single SOA Suite Install with multiple oc4j instances and java processes

We right now have 5 BPEL processes and 5 ESB processes all running under one java.exe process. We would like to seperate some of
them out into their own java.exe processes without having to install more
%ORACLE_HOME% instances of SOA Suite. I can create an oc4j instance but of
course it doesn't have any SOA Suite stuff deployed to it. I tried to see what
the install would do with this new oc4j instance but it wants to create a new
%ORACLE_HOME% with an entire installation of SOA Suite.
Is there some sort of way to clone oc4j instances that have SOA Suite deployed to them so that you
don't need multiple %ORACLE_HOME% instances?
### How is this Issue Impacting Your Business ###
We really don't want to have a lot of %ORACLE_HOME% instances to have to maintain. We are
migrating projects over from our current integration server product and we'll
have potentially dozens more BPEL and ESB projects. We definitely want to
group and isolate projects so that outages of one project do not bring down
others that are unrelated.
We are currently experiencing periodic problems with one BPEL project that requires recycling but all the other BPEL and ESB
projects get recycled also. If we could put this project into it's own java
process without creating another SOA SUITE instance, it would be a big
help.
ANSWER
=======
You can create multiple domains in BPEL or create multiple systems/groups in ESB to group different projects.
MY REPLY:
=========
We have been using systems/groups in ESB but they all run under the save java.exe process. I would assume that having a seperate domain in BPEL would also run in that same java.exe process.
Right now, the one BPEL project we have a problem with will gobble up all the JDBC connections from time to time and that requires a recycle of SOA Suite, which means all BPEL and ESB projects that run in that java.exe process get recycled also. We're working that issue in a different ticket.
It would be nice if the SOA Suite installation would install against a new oc4j instance and not assume it has to create a complete %ORACLE_HOME% instance. The components of SOA Suite seem to be J2EE based components.
Scenario: I already have an oc4j instance called oc4j_soa and a complete %ORACLE_HOME% installation of soa suite. I then create a new oc4j instance from Enterprise Manager. Then I would deploy the esb-dt, esb-rt, orabpel, etc. components of SOA Suite to that new oc4j instance and modify the necessary config file so that it can work with OHS and the SOA Suite Databases. Is this possible?
Does anyone have any experience with this or do people typically install multiple complete installation of SOA Suite with mulitple Oracle Homes?

Hi,
yes, on metalink you get in touch with real experts....
You have to install serveral application servers to get different ORACLE_HOMEs.
For each one, you can install a BPEL PM.
But: For each BPEL PM you need your own database instance, or you have to configure them as a clustered BPEL installation.... (but i do not know if this work with non RAC DBs)

Multiple Server Instances and Schedulers

Hi,
I am facing a huge problem with the schedulers.
I have multiple system ID's in my SAP portal.
Suppose i create a JAVA scheduler and export it (as PAR) in the portal, it shows up in the scheduler tasks but while scheduling it the problem is with the System ID. I have 9 instances of them. Rest of my schedulers runs on a particuler System ID but this one is not running there, insted when i checked i found its running over a different System ID.
I am completely unaware of this concept. Can anyone please explain or post any link regarding the same so that i can get an insight of the same.
Thanks in Advance.

Thanks Tushar,
I am not able to figure out on which system instance should I schedule my scheduler.
Previously I use to schedule it over a particular instance and it worked fine. But yesterday when I did the same it didn't worked, so i checked all the System ID's and found that it is working on two System ID's rathe than the one I used to normally schedule. So i am lost as to where should I schedule it in future for any other schedulers.
I am not able to figure out the concept of this multiple instance and its use. If you can refer to any document that might will be of great help to me.
Thanks and Regads,
Kunal.

Multiple ipods users and one computer

Our household has several iPods but use one computer. I just purchased a new iPod and when I connected to the computer (Windows XP) it allowed me to identify my ipod but sunced the other ipod user's music. I'm lost - how can I or can I maintain 2 different syncs?

When the iPods belong to different people, there are basically three ways of using multiple iPods on a computer and these involve:
a) Sharing a single iTunes library
b) Creating Multiple Libraries in a single user account
c) Creating multiple user accounts.
Note: When you are sharing an iTunes library, you don't have to set each iPod to update in the same manner, you can mix and match from the options below as each iPod has it's own update settings
Sharing a Library and/or User Account
If you want to share the one library, you can set either or all of the iPods so that they only get updated with only certain playlists (you can update from more than one if you wish): Loading songs onto iPod automatically - Windows
Choosing the update option "Sync Music - Selected playlists" allows you to create a playlist specifically for the iPod and drag the tracks you want into it. If you tire of the list and want to change it, you just add or remove the songs you don't want. The ones you take out out remain in the library to be used some other time if you choose. You can read more about playlists at these links:
iTunes: Creating playlists of your favorite songs
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Or you can choose to update any or all of the iPods manually and just drag whatever content you want to them: Managing content manually on iPod
Loading the iPod shuffle differs slightly but it can still be used with the others, for details have a look at this page: Loading songs onto iPod shuffle - Windows
Multiple Libraries
It's also possible to have multiple libraries in a single account. To create or access a second (or more) library, hold down the Shift key (or the Option key on a Mac) when launching iTunes 7. In the resulting dialogue you will get the option to create a new library or navigate to the other Library.
Note: You can only have one Library open at a time and iTunes will default to the last library opened if you don't use the keyboard command to choose one. This can prove tricky when using multiple iPods, if you don't use the keyboard command you can risk syncing to the wrong library: Using multiple iTunes libraries -Windows
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Another option is to create a separate User account for each person on your PC or Mac. Different accounts by definition would give you completely separate libraries. Each account has it's own iTunes folder, Library and iTunes Music folder and you load it with CDs etc just as you did with your original one. The iPod can be set to update however the owner chooses, sync all, manual or sync specific playlists
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Multiple JVM instances stop simultaneously.

We have a customer running JRE 1.5.0_8 on a Windows 2003 Server.
We have multiple java applications running in the background on this server. We keep having an intermittent problem where all of these java applications shutdown at the same time (I'm talking within the same second). It apparently is somewhat of a clean shutdown because our shutdown hooks are running; however, these programs should not be stopping. There are no dumps being created by the JVM. It happened twice yesterday, but the day before did not happen at all.
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I do not know what kind of Windows patches has been installed by the client.

ping

Running multiple vi instances and datasockets

Hi,
I have an application that may need several instances of one VI running. I am using Datasockets to transfer data and control other VIs. Is there a way to differentiate the same datasockets running on the different instances of the same VI?
Thanks,
Michael

Good Afternoon Michael,
Datasockets are simply sending data using the TCP/IP protocol; your packets are just data sent out from a port. As such, there is no default method to determine from which program/VI/instance of the same VI data was sent.
You can incorporate some kind of tag with your data which identifies the source of the data and simply parse that information out on the receiving end. An easy way to identify different instances of a sub-VI is to include an additional control on the VI and its connector pane. In this case, each instance of the VI will have a special identifier which can be passed along with the data to send.
Regards,
Charlie Piazza
Staff Product Support Engineer, RF
National Instruments

Multiple Portal Instances and Cookie Names

i have three portal instances (3.0.7) under the same database 8.1.7 on NT.
for example:
portal30 + portal30_sso
myportal + myportal_sso
testportal + testportal_sso
actually i cannot work on more than one portal at the same time. so, each time i want to work under a particular portal i make sure i am not logged in the other two.
if i assign a different COOKIE NAME in the
GATEWAY for each DAD it will fix my problem?
any suggestion?
tks!!

i will appreciate some answer to this posting.
tks!

Multiple database instances and JDBC

The data I need resides in two different database instances. Can I make two jdbc calls to two different instances, in the same java code?Any better suggestions?? Please.

No, you don't need to close the first before creating the second one.
The connections will be entirely unrelated unless (as duffy indicates) you need to wrap the operation in a transaction so that they will either complete together, or not at all. If the operations are unrelated, there is no need to do this.
Dave.

Multiple application instances and inter process communication.

Hi,
I am looking at having a main application instance spawn individual application instances. But when launching another instance I need to message the main application so it can spawn a window.
How do I go about communicating between application instances in order to do this ?
Many thanks in advance,
Aaron

RMI is your best bet - or, if the IPC is pretty simple, then you could just open a simple socket listener in the primary app...
- K

Multiple Ultrabeat instances cause pops/clicks unrelated to system performance

Hi folks,
Recently I started having the oddest of issues:
I haven't used ultrabeat in the longest of times. I opened up a few old projects with multiple ultrabeat instances and was getting some weird pops/clicks on transients when multiple Ultrabeat instances were present.
If I mute them, the problems persist. But as soon as I rid the project of all but a single instance the issue goes away.
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Thanks!

I'm tempted to say this isn't an I/O buffer issue... as it happens at any latency setting... (from 32 to 1024) and only with Ultrabeat in use on multiple tracks.
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Multiple JVM's in one JDK

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.
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Multiple Portal instances on the same machine

Hi Forum,
we have a requirement where in we are asked to implement multiple instances of Portal on the same machine. can you please give me some detials on Feasibility , issues and limitations of having multiple Portal instances on the same machine , different instances pointing to different tiers(Dev, Test, Production) etc
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regards,
uday

Hi Uday,
Please look at this.
Multiple Portal Instances - Virtual Hosting
Regards,
Siva
P.S: Award points if you find this useful.

Multiple JVM instances and host computer performance

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