Recommended Heap Size

Hi,
I see a lot of talk about upping/modifying the following parameters:
MaxPermSize=128M -ms512M -mx1024M
where folk are getting into difficulties with out of memory.
We don't have out of memory, but I'm trying to find info on how to make the best of these settings for optimal server usage, but I'm a bit vague as to what these even mean!
We have an 8GB quad-processor Linux RH4 running HTTP/J2EE 10.1.3.1.0, so think that we could up these values to makes sure all run smoothly. However, if I double these values, what effects will it have, and to what? Will the server suddenly fail, OC4J collapse? It's a live system, so I don't want to play, but happy to tweak where a concensus suggests so.
Anyone seen any recommendations, or some sort of best practice document, anywhere?
Thanks in advance
Iain

http://www.weblogic.com/docs51/admindocs/tuning.html#jvm execution
Srikant, [email protected], http://weblogic.bea.com/, etc.
kevin wrote:
We have two gigs of RAM, load testing not necessary at this stage of development. Any recommendations for heap size?
thanks.

Similar Messages

Recommended heap sizes for Dev/Live/Shared CF boxes

Hi all
I've searched through all the relevant past posts, but most of them were posted before CF8.0.1 going 64-bit, so the situation has changed slightly.
What are people's opinions on heap sizes for various server setups? I have my dev server - I leave this on 512MB and that's fine for most of the stuff I do. We generally up this to a gig on our live servers (which only run 3-4 small sites), and historically we've not gone above this on our Shared servers (which host anywhere up to 400 sites) because of the 32-bit limit.
However, now we're running CF9 on 64-bit Server 2008, we've obviously got a lot more RAM available. The obvious choice is to ramp it up high, but I've also been heard that causes issues of its own - the Java GC then has far more work to do when it's called and as the memory fills it's harder to get a contiguous block of RAM, so performance can suffer.
Does anyone have any experience of running Shared servers, or busy sites? The Server monitor is great for tuning maximum threads and the suchlike, but I can't really sit in front of it for hours waiting for the heap to fill. Also, our live servers are only Standard edition, so there's no Server Monitor.
Thoughts?
Ta
O.

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I have my dev server - I leave this on 512MB and that's fine for
most of the stuff I do. We generally up this to a gig on our live
servers (which only run 3-4 small sites), and historically we've not
gone above this on our Shared servers (which host anywhere up to 400
sites) because of the 32-bit limit.
However, now we're running CF9 on 64-bit Server 2008, we've obviously got a lot more RAM available. The obvious choice is to ramp it up high, but I've also been heard that causes issues of its own - the Java GC then has far more work to do when it's called and as the memory fills it's harder to get a contiguous block of RAM, so performance can suffer.
Leave the memory setting at the default value, until testing requires you to do otherwise, or your sites unravel some unforeseen memory demand. It's a risk our SysAdmin colleagues are prepared to take. With the coming of 64-bit, they've been on the alert, and have always cattle-prodded us whenever we've been tempted to push the button to go higher.
Our defaults almost coincide with yours: 512 MB for 32-bit and just over 1GB for 64-bit. So what you yourself have just said is my own basic wisdom on the subject, too: if it aint broke, don't try to fix it.
[postscript: I work full-time at one company, part-time at another. By pure coincidence, both use the same JVM memory settings.]

Large heap sizes, GC tuning and best practices

Hello,
I’ve read in the best practices document that the recommended heap size (without JVM GC tuning) is 512M. It also indicates that GC tuning, object number/size, and hardware configuration play a significant role in determining what the optimal heap size is. My particular Coherence implementation contains a static data set that is fairly large in size (150-300k per entry). Our hardware platform contains 16G physical RAM available and we want to dedicate at least 1G to the system and 512M for a proxy instance (localstorage=false) which our TCP*Extend clients will use to connect to the cache. This leaves us 14.5G available for our cache instances.
We’re trying to determine the proper balance of heap size vs num of cache instances and have ended up with the following configuration. 7 cache instances per node running with 2G heap using a high-units value of 1.5G. Our testing has shown that using the Concurrent Mark Sweep GC algorithm warrants no substantial GC pauses and we have also done testing with a heap fragmentation inducer (http://www.azulsystems.com/e2e/docs/Fragger.java) which also shows no significant pauses.
The reason we opted for a larger heap was to cut down on the cluster communication and context switching overhead as well as the administration challenges that 28 separate JVM processes would create. Although our testing has shown successful results, my concern here is that we’re straying from the best practices recommendations and I’m wondering what others thoughts are about the configuration outlined above.
Thanks,
- Allen Bettilyon

Hello,
I’ve read in the best practices document that the recommended heap size (without JVM GC tuning) is 512M. It also indicates that GC tuning, object number/size, and hardware configuration play a significant role in determining what the optimal heap size is. My particular Coherence implementation contains a static data set that is fairly large in size (150-300k per entry). Our hardware platform contains 16G physical RAM available and we want to dedicate at least 1G to the system and 512M for a proxy instance (localstorage=false) which our TCP*Extend clients will use to connect to the cache. This leaves us 14.5G available for our cache instances.
We’re trying to determine the proper balance of heap size vs num of cache instances and have ended up with the following configuration. 7 cache instances per node running with 2G heap using a high-units value of 1.5G. Our testing has shown that using the Concurrent Mark Sweep GC algorithm warrants no substantial GC pauses and we have also done testing with a heap fragmentation inducer (http://www.azulsystems.com/e2e/docs/Fragger.java) which also shows no significant pauses.
The reason we opted for a larger heap was to cut down on the cluster communication and context switching overhead as well as the administration challenges that 28 separate JVM processes would create. Although our testing has shown successful results, my concern here is that we’re straying from the best practices recommendations and I’m wondering what others thoughts are about the configuration outlined above.
Thanks,
- Allen Bettilyon

Managed Servers vs. Admin Server - heap sizes

I have a question. I opened a support ticket with BEA yesterday, the technician got back to me and completely confused the hell out of me.
We're looking to upgrade to WLS10 with an admin server/managed server design. I was under the impression that each server instance, when fired up, starts up in its own JVM with its own memory allocations. If I set the admin server startup script to have a min and max of 1024, the managed server starts up with the same memory settings. The technician I spoke with yesterday from BEA support to clarify this then explains to me that each server instance, admin and managed, do not exist in their own JVMs but that they share the same JVM. I found verbage in the documentation that says the complete opposite...that one server instance can only exist in one JVM...SO if I have the admin server with 1024 and the managed server with 1024 and the machine only has 2 gigs, that's pretty much all I can have running on this machine, right?
The thing I don't understand at all is why would I want the admin server and my application on the managed server to use the same amount of ram? My managed server should have way more ram available to it than the admin server which is rarely used throughout the day. Is there a way to set the admin server to 512 and then fire up the managed server with a gig and a half?
I would think it makes more sense that you specify a different heap size for the admin versus the managed...but maybe not. What is the recommended heap size for the admin server? Is it strictly recommended to let them all use the same heap size settings? Can someone explain why I'd want the admin server to have access to the same amount my heavyweight, client-hit-all-day-long application?
Any help would be greatly appreciated.
Cheers,
rlb

Thanks David. As God as my witness, the tech seriously told me that they all use the same JVM. Then I got seriously confused, like I was an idiot and didn't understand what a JVM was and I started second-guessing myself. The whole conversation was very strange and yes, there was definitely a language barrier and I'm guessing I just wasn't being clear enough...I don't know...all I know is I walked away from the phone call in worse shape then when I first opened the ticket.
At any rate, do you have recommendations for admin server ram? I know there are performance tuning tools to help us figure out the optimum settings for our managed server, and I plan on implementing them...but going back to the ram for the Admin server, versus managed server...is there a recommended way of specifying different heap size for the managed servers? Is the recommended way to set the the -Xms and -Xmx settings via the 'Arguments' field on Environment > Servers > serverName > Configuration > Server Start tab via the admin console?
Thanks again for your quick reply!
Cheers,
rlb

Plz can you help me. How to increase the Heap Size!!!!!!!!!!!

Hi,
i'm new to 10g appl server
Failed to deploy web application "AGXI51". Failed to deploy web application "AGXI51". . The evaluate phase failed. The Adapter used in the evaluate may have thrown an exception.
Resolution:
Please call Oracle support.
Base Exception:
java.lang.OutOfMemoryError
null. java.lang.OutOfMemoryError
i'm getting this Error while deploying the application.So wat is the procedure to increase the Heap Size
Regards,
Niranjan.D

Locate opmn.xml on your instance. In file locate section relevant for container you use (i.e. "home"). In next line you can see tags where startup parameters are set. You should add following parameters (this will set heap size on 512Mb)
-Xms512m -Xmx512m
For detailed explanation I would recommend you to check following link:
http://download-uk.oracle.com/docs/cd/B25221_03/web.1013/b14431/troublesht.htm
Hope this help.

How to increase the heap size of the container in whioch BPEL is running ?

Hi All,
I recently raised an SR they have asked me to do the following,
Can you please try and start the container running the BPEL process with max
heap space (-Xmx) of 2 GB and the eden space (-Xmn) at about 60% of 1228m and
the option -XX:+AggressiveHeap set. (even though this option is recommended for
multi processor machines say 4)
can anyone kindly explain me how to increase the Heap size and Eden size of BPEL container ?
Thank You

Hi Deepak I cant see any attribute or element in the oc4j_opmn.xml file regarding heap memory. In the server properties I changed the size of heap memeory how can I rollback.
I am getting the following error
Configuration information
Running in C:\product\10.1.3.1\OracleAS_1
Operation mode:Startup, App Server, No Enterprise Manager, Single Instance
Oracle home:C:\product\10.1.3.1\OracleAS_1
Oracle home name:Unnamed
Instance name:SOA.01hw117905.India.TCS.com
Instance type:allProducts
Version:10.1.3.4.0
Uses infrastructure:false
Not an infrastructure instance, no infrastructure information available
Components:[j2ee, apache, orabpel, oraesb, owsm, Wsil]
2009-08-19 09:08:51.863--Begin log output for Mid-tier services (SOA.01hw117905.India.TCS.com)
2009-08-19 09:08:51.863--Processing Step: starting OPMN
2009-08-19 09:09:00.394--Processing Step: starting OPMN managed processes
2009-08-19 09:09:35.19--End log output for Mid-tier services (SOA.01hw117905.India.TCS.com)
An unknown OPMN error has occured
oracle.appserver.startupconsole.model.ConsoleException: An unknown OPMN error has occured
     at oracle.appserver.startupconsole.control.OPMNController.doStart(OPMNController.java:121)
     at oracle.appserver.startupconsole.control.Controller.start(Controller.java:69)
     at oracle.appserver.startupconsole.control.GroupController.doStart(GroupController.java:47)
     at oracle.appserver.startupconsole.control.Controller.start(Controller.java:69)
     at oracle.appserver.startupconsole.view.controller.ControllerAdapter.start(ControllerAdapter.java:30)
     at oracle.appserver.startupconsole.view.controller.MasterControlAdapter.run(MasterControlAdapter.java:94)
     at oracle.appserver.startupconsole.view.Runner.main(Runner.java:39)
Caused by: oracle.ias.opmn.optic.OpticControlException: Error from opmn during process control operation
     at oracle.ias.opmn.optic.AbstractOpmnEntity.runCommand(AbstractOpmnEntity.java:174)
     at oracle.ias.opmn.optic.AbstractOpmnEntity.start(AbstractOpmnEntity.java:110)
     at oracle.appserver.startupconsole.control.OPMNController.doStart(OPMNController.java:89)
     ... 6 more
Exception caused by
Error from opmn during process control operation
oracle.ias.opmn.optic.OpticControlException: Error from opmn during process control operation
     at oracle.ias.opmn.optic.AbstractOpmnEntity.runCommand(AbstractOpmnEntity.java:174)
     at oracle.ias.opmn.optic.AbstractOpmnEntity.start(AbstractOpmnEntity.java:110)
     at oracle.appserver.startupconsole.control.OPMNController.doStart(OPMNController.java:89)
     at oracle.appserver.startupconsole.control.Controller.start(Controller.java:69)
     at oracle.appserver.startupconsole.control.GroupController.doStart(GroupController.java:47)
     at oracle.appserver.startupconsole.control.Controller.start(Controller.java:69)
     at oracle.appserver.startupconsole.view.controller.ControllerAdapter.start(ControllerAdapter.java:30)
     at oracle.appserver.startupconsole.view.controller.MasterControlAdapter.run(MasterControlAdapter.java:94)
     at oracle.appserver.startupconsole.view.Runner.main(Runner.java:39)
<?xml version='1.0' encoding='WINDOWS-1252'?>
<response>
<msg code="-82" text="Remote request with weak authentication.">
</msg>
<opmn id="01hw117905:6200" http-status="206" http-response="2 of 3 processes started.">
<ias-instance id="SOA.01hw117905.India.TCS.com">
<ias-component id="default_group">
<process-type id="home">
<process-set id="default_group">
<process id="172" pid="2176" status="Alive" index="1" log="C:\product\10.1.3.1\OracleAS_1\opmn\logs\\default_group~home~default_group~1.log" operation="request" result="success">
<msg code="0" text="">
</msg>
</process>
</process-set>
</process-type>
<process-type id="oc4j_soa">
<process-set id="default_group">
<process id="173" pid="5556" status="Stopped" index="1" log="C:\product\10.1.3.1\OracleAS_1\opmn\logs\\default_group~oc4j_soa~default_group~1.log" operation="request" result="failure">
<msg code="-21" text="failed to start a managed process after the maximum retry limit">
</msg>
</process>
</process-set>
</process-type>
</ias-component>
<ias-component id="HTTP_Server">
<process-type id="HTTP_Server">
<process-set id="HTTP_Server">
<process id="171" pid="2724" status="Alive" index="1" log="C:\product\10.1.3.1\OracleAS_1\opmn\logs\\HTTP_Server~1.log" operation="request" result="success">
<msg code="0" text="">
</msg>
</process>
</process-set>
</process-type>
</ias-component>
</ias-instance>
</opmn>
</response>

Getting exception after increasing the heap size

Hi ,
I have increased the heap size of my manged server from 512MB to 1024MB and started the server. When I tried to post the messages to queue I am getting the below exception and my managed server is going down. Weblogic server version is 10.3.0. Could you please help me to resolve this issue. It is verr urgent
******* EXCEPTION FROM THE MAIN METHOD -Generic Exception *******
weblogic.jms.common.JMSException: weblogic.messaging.dispatcher.DispatcherException: weblogic.rjvm.PeerGoneException: No message was received for: '240' seconds
at weblogic.jms.dispatcher.DispatcherAdapter.convertToJMSExceptionAndThrow(DispatcherAdapter.java:116)
at weblogic.jms.dispatcher.DispatcherAdapter.dispatchSyncTran(DispatcherAdapter.java:53)
at weblogic.jms.client.JMSProducer.toFEProducer(JMSProducer.java:1271)
at weblogic.jms.client.JMSProducer.deliveryInternal(JMSProducer.java:783)
at weblogic.jms.client.JMSProducer.sendInternal(JMSProducer.java:541)
at weblogic.jms.client.JMSProducer.sendWithListener(JMSProducer.java:394)
at weblogic.jms.client.JMSProducer.send(JMSProducer.java:384)
at weblogic.jms.client.WLProducerImpl.send(WLProducerImpl.java:970)
at QueueSendConfig.send(QueueSendConfig.java:88)
at QueueSendConfig.main(QueueSendConfig.java:126)
Caused by: weblogic.messaging.dispatcher.DispatcherException: weblogic.rjvm.PeerGoneException: No message was received for: '240' seconds
at weblogic.messaging.dispatcher.DispatcherWrapperState.dispatchSyncTran(DispatcherWrapperState.java:350)
at weblogic.jms.dispatcher.DispatcherAdapter.dispatchSyncTran(DispatcherAdapter.java:51)
... 8 more
Caused by: weblogic.rjvm.PeerGoneException: No message was received for: '240' seconds
at weblogic.rjvm.ResponseImpl.getThrowable(ResponseImpl.java:202)
at weblogic.messaging.dispatcher.DispatcherProxy.unmarshalResponse(DispatcherProxy.java:253)
at weblogic.messaging.dispatcher.DispatcherProxy.dispatchSyncTranFuture(DispatcherProxy.java:134)
at weblogic.messaging.dispatcher.DispatcherWrapperState.dispatchSyncTran(DispatcherWrapperState.java:338)
Thanks & Regards
James

Hi James,
weblogic.rjvm.PeerGoneException is basically caused due to a network failure between the peers like message producer and the consumer failing to communicate in the specified time frame.
240 seconds is the default value for the t3 connection timeout, if the peer is not getting response for 240 seconds. Then it would timed out.
This value can be tuned, however it is not recommended.
Can you check the network traffic and see if any network glitches causing the issue?
Also check whether you are trying to send large messages over a slow network causing the delay.
You can capture the thread dumps as well to get more insights on the issue.
Cheers,
Andy

How to increase Memory and Java Heap Size for Content Server

Hi,
My content server is processing requests very slowly. Over performance is not good. I have 2 GB of RAM any idea what files I can modify to increase the Java Heap Size for the Content Server. If I increase the RAM to 4 or 6 GB where do I need to make changes for the Java Heap Size and what are the recommended values. I just have Content Server Running on the linux box. Or how do I assign more memory to the user that owns the content server install.
Thanks

You might find these interesting:
http://blogs.oracle.com/fusionecm/2008/10/how_to_-javatuning.html
http://download.oracle.com/docs/cd/E10316_01/cs/cs_doc_10/documentation/admin/performance_tuning_10en.pdf
Do you have access to metalink? This has about everything you could want:
https://metalink2.oracle.com/metalink/plsql/f?p=130:14:9940589543422282072::::p14_database_id,p14_docid,p14_show_header,p14_show_help,p14_black_frame,p14_font:NOT,788210.1,1,1,1,helvetica
Or search for "788210.1" in metalink knowledgebase if that link doesn't work and look for the FAQ on configuring Java for Content Servers

Setting memory heap size

Hi,
I would like to know how to set the default memory
heap size to 128 MB while installing the Java Plugin
itself.
Is there any environment variable available for setting
this?
I dont want to use the Control Panel option for setting
it.
Thanks for your help.

Hey i have the same issue, how did you solve it?
Hi Gkumarc1,
Plugin 1.3.0 (and after) reads the property filein
.java directory of user's home directory. Java
runtime parameter is saved in the property file.Here
is an example of it:
# Java(TM) Plug-in Properties
# DO NOT EDIT THIS FILE. It is machine generated.
# Use the Activator Control Panel to editproperties.
javaplugin.jre.params=-Xmx 128m
Hope this helps.
Sun-DTSIs there a way to set the default heap size on the
fly? Meaning, we want to avoid the need for our
customers to go into their control panel and make
this setting. Instead, we would like to have the
applet load with our preferred default VM size. This
would allow us to change the preferred size during
some future performance enchancements without having
to contact all of our 2,000+ external customers. Is
there something that can be put in the PARAM tag
within the HTML that specifies the
preferred/recommended default size?
Any help would be greatly appreciated.

Heap sizes with Planning11.1.1.3 & Weblogic help

I'm used to having the xms and xmx heap sizes in the registry with planning. But i installed Planning 11.1.1.3 with weblogic 9.2 (all 32 bit) and deployed as a service. However, the registry does not have the usually heap settings automatically added. I can modify the setDomainEnv script to bump up heap sizes but running that script leaves the command window running in the foreground which is something i don't want. I tried manually adding the heap size settings to the Hyperion Planning registry settings, but they are not taking effect when starting the web server via the services console. Anyone have any ideas. I peaked around the web logic admin console but i didnt really want to try and set the heap sizes through there. plus, i'm not sure any settings in there will take effect when starting from the service console. I thought all the arguments for a service are derived from the registry.

EssbaseInAz wrote:
"We are using 64bit Windows 2003 with Weblogic 9.2 as well. What is the heap size suggestions in Hyperion Planning 11.1.1.3?"
Are the heap sizes already present in your planning registry setting? Did you use the jrockit jvm or the sun jvm when configuring Weblogic. I'm trying to track down what caused my install not to create the heap size jvmoption in my registry. I know Weblogic recommends using the jrockit jvm for performance reasons, but if i can't get the planning service to run with larger heaps, i may have to change jvms. Having the planning web running in the foreground seems to risky for me (someone logging out and shutting down any running windows).We are using Jrockit JVM and the heap size setup is around 1GB.
As John mentioned, 1.8GB may be the max even though you are using 64bit version.

How to adject ABAP HEAP SIZE???

Hi,
How do I adjust ABAP Heap size..??
any step by step or note?
Thanks,

Hi Afi,
you can get some information here:
http://help.sap.com/saphelp_nw04s/helpdata/en/7a/caa6f3bfdb11d188b30000e83539c3/frameset.htm
There you will also find the parameters:
abap/heap_area_dia: Heap Memory Limit for Dialog Work Processes
abap/heap_area_nondia: Heap Memory Limit for Non-Dialog Work
abap/heap_area_total: Total Quota for Heap Memory
and recommendations how to configure them.
Have a look and award points if useful.
Rgds,
Loukas

How do we monitor Java heap size

How do we monitor Java heap size? Is there any way to check whether we are exceeding the heap size or not?
Regards,
N.S

Hi,
> How do we monitor Java heap size? Is there any way to
> check whether we are exceeding the heap size or not?
>
You should run your JAVA AS with the recommended settings described in the note
"Java VM settings for J2EE 6.30/6.40/7.0"
SAP Note Number: 723909.
If you do so, you can find the garbage collector log messages in your dev_server* or your std_server*.out file.
You can also use the option -Xloggc:<file> to log to a seperate file.
You can visualize the GC log file with a tool like GCViewer.
See
http://www.javaperformancetuning.com/tools/gcviewer/index.shtml
for an overview of this tool.
Regards,
Markus

Java Heap Sizes -Xms -Xmx

Gurus,
Could some body help me to understand the differentiate between heap size parameters -Xms and -Xmx ? I usually change both of them. One another is that, the maximum heap size we can use is total ram/2 ?
Thanks,

Text from the above link
==================
As part of the Best Practices, we know that we should be setting -Xms & -Xmx Java command line parameters. What are these settings and why is it required to set these.
As JAVA starts, it creates within the systems memory a Java Virtual Machine (JVM). JVM is where the complete processing of any Java program takes place. All JAVA applications (including IQv6) by default allocates & reserves up to 64 MB of memory resource pool from the system on which it is running.
The Xms is the initial / minimum Java memory (heap) size within the JVM. Setting the initial memory (heap) size higher can help in a couple of ways. First, it will allow garbage collection (GC) to work less which is more efficient. The higher initial memory value will cause the size of the memory (heap) not to have to grow as fast as a lower initial memory (heap) size, thereby saving the overhead of the Java VM asking the OS for more memory.
The Xmx is the maximum Java memory (heap) size within the Java Virtual Memory (JVM). As the JVM gets closer to fully utilizing the initial memory, it checks the Xmx settings to find out if it can draw more memory from the system resources. If can, it does so. For the JVM to allocate contiguous memory to itself is a very expensive operation. So as the JVM gets closer to the initial memory, the JVM will use aggressive garbage collection (to clean the memory and if possible avoid memory allocation), increasing the load on the system.
If JVM is in need of memory beyond the value set in Xmx, the JVM will not be able to draw more memory from system resource (even if available) and run out of memory. Hence, the -Xms and -Xmx memory parameters should be increased depending upon the demand estimation of the system. Ideally both same should be the same value (set at maximum possible as per demand estimation). This ensure that the maximum memory is allocated right at the start-up eliminating the need for extra memory allocation during program execution. We recommend aggressive maximum memory (heap) size of between 1/2 and 3/4 of physical memory.
Edited by: oracleSQR on Oct 7, 2009 10:38 AM

The initial heap size must be less than or equal to the maximum heap size.

All,
Please help!!
I have tested my Application Client Project in WSAD on my pc and it works fine.
I have 1gb RAM on my pc. When I deploy the same app on another xp pc(same as mine but 512mb RAM) I get a heap size error. Here is the exact error:
Incompatible initial and maximum heap sizes specified:
initial size: 268435456 bytes, maximum heap size: 267380736 bytes
The initial heap size must be less than or equal to the maximum heap size.
The default initial and maximum heap sizes are 4194304 and 267380736 bytes.
Usage: java [-options] class [args...]
(to execute a class)
or java -jar [-options] jarfile [args...]
(to execute a jar file)
where options include:
-cp -classpath <directories and zip/jar files separated by ;>
set search path for application classes and resources
-D<name>=<value>
set a system property
-verbose[:class|gc|jni]
enable verbose output
-version print product version
-showversion print product version and continue
-? -help print this help message
-X print help on non-standard options
Could not create the Java virtual machine.
Press any key to continue . . .
Here is the batch file that runs my app:
@echo off
SET appClientEar=C:\corp\apps\mts\jars\MTSClientEAR.ear
set JVM_ARGS=-Xms256M -Xmx256M
set CLIENT_PROPS=C:\corp\apps\mts\jars\medicalclient.properties
set APP_ARGS=
call C:\bnsf\IBM\WebSphere\AppClient\bin\launchClientBNSF.bat "%JVM_ARGS%" %appClientEar% "-CCpropfile=%CLIENT_PROPS%" %APP_ARGS%
@pause
I have changed the value of Xms and Xmx of JVM_ARGS to different size but I sitll get error. Anyone knows what the problem is. Thanks..

Don't know why, but the "maximum heap size: 267380736 bytes" value is just slightly less than 256*1024*1024, wheras the reported initial size is equal to that.
Try setting the initial value to 255MB.

What is the best way to verify default heap size in Java

Hi All,
What is the best way to verify default heap size in Java ? does it vary over JVM to JVM . I was reading this article http://javarevisited.blogspot.sg/2011/05/java-heap-space-memory-size-jvm.html , and it says default size is 128 MB but When I run following code :
public static void main(String args[]) {
int MB = 1024*1024;
System.out.println(Runtime.getRuntime().totalMemory()/MB);
It print "870" i.e. 870 MB.
I am bit confused, what is the best way to verify default heap size in any JVM ?
Edited by: 938864 on Jun 5, 2012 11:16 PM

938864 wrote:
Hi Kayaman,
Sorry but I don't agree with you on verification part, Why not I can verify it ? to me default means value when I don't specify -Xms and -Xmx and by the way I was testing that program on 32 bit JRE 1.6 on Windows. I am also curious significant difference between 128MB and 870MB I saw, do you see anything obviously wrong ?That spec is outdated. Since Java 6 update 18 (Sun/Oracle implementation) the default maximum heap space is calculated based on total memory availability, but never more than 1GB on 32 bits JVMs / client VMs. On a 64 bits server VM the default can go as high as 32gb.
The best way to verify ANYTHING is to address multiple sources of information and especially those produced by the source, not some page you find on the big bad internet. Even wikipedia is a whole lot better than any random internet site IMO. That's common sense, I can't believe you put much thought into it that you have to ask in a forum.

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