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| mqsichangeconfigmgr -j : Can it solve performance problems? |
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| Helikopter99 |
 Posted: Sun Jul 29, 2001 7:54 am Post subject: |
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Newbie
Joined: 12 Jul 2001
Posts: 4
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Hi all,
Command: mqsichangeconfigmgr -j :
(Explanation MQSI 2.0.1 Admin guide:)
-j MaxJVMHeapSize
The maximum Java virtual machine (JVM) heap size, in megabytes. The
smallest value that may be set is 64. If this parameter is not set, the default size
of 128 MB is used.
If you would higher this value, what does this mean?
That more developers will be able to work remote on one configuration manager?
Why exactly needs MQSI JVM for?
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| kolban |
| Posted: Sun Jul 29, 2001 8:48 am Post subject: |
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Grand Master
Joined: 22 May 2001
Posts: 1072
Location: Fort Worth, TX, USA
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Apparently at least part of the Configuration Manager is implemented in Java. Since Java requires its own Virtual Machine (Java Virtual Machine) and this is bascially a "logical" computer within the computer, that computer must be allocated its own heap for storage to prevent some form of memory run-away.
My basic understanding of the JVM heap-size is that it should only be increased if the program (Configuration Manager in this case) needs more memory. I don't believe that increasing its size will result in any better performance characteristics. |
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| chrisfra |
| Posted: Mon Jul 30, 2001 7:17 am Post subject: |
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Novice
Joined: 24 Jun 2001
Posts: 14
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This option was added to address a problem that was seen when trying to deploy very large message flows on MQSI V2 on NT. The deploy would take so long that it would eventually time out. This was bad because any subsequent activity (like deploying again, or even doing a log refresh) would then also time out.
The deploy would fail because the Configuration Manager's JVM would run out of memory (portions of the ConfigMgr are written in Java). The JVM heap size was fixed at 128MB and could not be changed in V2.0 (unless you wanted to edit the NT Registry). What added insult to injury was that when this probelm occurred, no messages are written to the NT Event Log to tell you that this was happening. This new "j" option was introduced as a way to easily increase the JVM heap value for Configuration Manager instances where this problem was encountered.
So, this option is not really intended to improve performance, but rather to resolve a problem where too little virtual memory was available in a specific circumstance. I doubt it would deliver any real benefit if the JVM size is sufficiently large already, and using it in this case could have a negative effect, as it could lead to thrashing.
Regards,
Christopher Frank
Software I/T Specialist
Transformation & Integration Software
Central Region, IBM Americas
IBM Certified Solutions Expert - MQSeries
Phone: 612-397-5532 (t/l 653-5532)
e-mail: chrisfra@us.ibm.com |
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| Helikopter99 |
| Posted: Mon Jul 30, 2001 11:03 am Post subject: |
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Newbie
Joined: 12 Jul 2001
Posts: 4
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| Thanks very much for your good explanation! |
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| kspranava |
| Posted: Thu Feb 19, 2004 1:34 am Post subject: is there any option |
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Centurion
Joined: 27 Apr 2003
Posts: 124
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Hi,
Is there any option to specify the JVM heapsize at the time of creating configmgr?
Pranava. |
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