>>Does anyone have any tuning/performance references/links for Java under >z/OS? >> >>Some tentative footsteps were taken to develop Java apps to run under USS >and the "Hello World" app sucked down 30% of the CPU during the time the >app was running. :( So, I gotta prepare for the onslaught when things really >kick into high gear. >> >>Thanks. >> >One thing you can do with a relatively short running Java jobs is to use the - >Xquickstart argument: > >-Xquickstart >Used for improving startup time of some Java applications. -Xquickstart >causes the JIT to run with a subset of optimizations; that is, a quick compile. >This quick compile allows for improved startup time. -Xquickstart is appropriate >for shorter running applications, especially those where execution time is not >concentrated into a small number of methods. -Xquickstart can degrade >performance if it is used on longer-running applications that contain hot >methods. The implementation of -Xquickstart is subject to change in future >releases. > >java -Xquickstart HelloWorld > >Refer to the Java InfoCenters depending upon your version: > >Java 1.4.2 - http://publib.boulder.ibm.com/infocenter/javasdk/v1r4m2/index.jsp > >Java 5 - http://publib.boulder.ibm.com/infocenter/javasdk/v5r0/index.jsp > >And the Java for z/OS home page: >http://www.ibm.com/servers/eserver/zseries/software/java/ > >I suppose if you are using JZOS, then you would add the -Xquickstart switch >to the IBM_JAVA_OPTIONS variable. > >Aaron
Another thing you can do if you are using Java 5 is shared classes. It can help reduce your footprint and improve your start-up time. You should definitely read about it before you use it heavily, though. So, the simplest one would be: java -Xshareclasses HelloWorld First time through might not be as fast, as it has to populate the cache. After that, it definitely helps. http://publib.boulder.ibm.com/infocenter/javasdk/v5r0/topic/com.ibm.java.doc. diagnostics.50/diag/understanding/shared_classes.html Aaron ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
