Java on OpenVMS - optimising performance (641 Views)
Frequent Advisor
Posts: 194
Registered: ‎06-01-2006
Message 1 of 5 (641 Views)

Java on OpenVMS - optimising performance



I have a java program that I am running on my OpenVMS Integrity.


The Java version is:-


$ java -version        

java version "6.0"

Java (TM) SE Runtime Environment

Java HotSpot (TM) 64-Bit Server VM (build 1.6.0-1 06/25/2009-12:58 IA64 (c2)W,m)



I invoke the program with:-


$ java -jar dsa4:[]PRDLoggerProd.jar "PRDTRANSPORTER"


But it runs very slowly. Not sure of this is because it has to first load and start java.


Any tips on optimising java for OpenVMS would be appreciated.





Honored Contributor
Posts: 6,593
Registered: ‎05-19-2003
Message 2 of 5 (607 Views)

Re: Java on OpenVMS - optimising performance

'runs very slowly' does not give us much to go on.


- compared to what?

- can tell what progress is is making? why do you think it is not reasonable?

- can you enable or add logging to further understand where it is spending time? 

- what is it doing? Consuming CPU? DIRIO? BUFIO Pagefaulting?

- Network interaction involved?

- Database involved?

- logging to a sequential file, byte-by-byte, allocating block-by-block?






Trusted Contributor
Posts: 385
Registered: ‎01-20-2005
Message 3 of 5 (595 Views)

Re: Java on OpenVMS - optimising performance

Hi Andrew,


Firstly, if you're running Java 1.6 (which would appear to be the case), install the latest Java patch kit which fixes some problems with alignment faults.  This might give an instant performance improvement.


Secondly, you should have a look at the Java for OpenVMS documentation at

which includes hints & tips for correct Java environment setup and performance.



Jeremy Begg


Valued Contributor
Posts: 198
Registered: ‎10-29-2010
Message 4 of 5 (294 Views)

Re: Java on OpenVMS - optimizing performance

Hi Andrew,


First Java in server mode runs less your code than Java in client mode. And Java/VMS ought to exclusively execute in server mode. And this explains why Java/VMS is only good at executing huge Java bytecode. For a good comparison between the two Java modes, I refer you to the Java obtained performances figures at


To be more complete, I very recently discovered JRockit, thanks to an Iranian of my knowledge. JRockit offers a JVM which should performance place itself in between Java server and Java client modes. My best summary upon JRockit was this URL link at which fully addressed my Google query : "What is JRockit ? Which need does cover JRockit ?"


In the hope this answer better address your concern.



Valued Contributor
Posts: 198
Registered: ‎10-29-2010
Message 5 of 5 (289 Views)

Re: Java on OpenVMS - optimizing performance



If you paid enough attention to this sentence in the second URL I posted and that I quote:


A handful of core classes have been modified for better performance, but the majority of classes are unchanged from the Sun JVM.


JRockit benefits are not innocent. It should be at the cost of some non Java standard methods. This can explain why JRockit is an Oracle requirement to execute Weblogic and why Weblogic ought to NOT be supported under OpenVMS.


My remark is in case you did read the second URL link I posted too fastly.




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