JVM Pooling – why you want to use it

Published by Peter McLarty | Filed under Application Server, Fusion Middleware

There is a feature in the 11g which was also available in 10g called JVM Pooling. It is simple enough to understand and the documents explain it reasonably well
JVM pooling is something that anyone that needs to run multiple instances of the Forms Runtime needs to consider whether to use JVM Pooling. It’s main purpose is to reduce memory usage by utilising a single JVM to support multiple Forms Runtime Services.
Enterprise Manager is the easiest way to create a new controller in the Application server, this controller manages the JVM

After creating a JVM, the process is relatively simple to configure the jvm to be used as a pooled resource. it needs a few entries in the formsweb.cfg otherparams=jvmcontroller=bigjvmController. If this is defined as a global value then any forms service when it starts will associate with the JVMcontroller that is defined as the global value else if a runtime process has its own JVM defined then it shall use that JVM

One of the great features of JVM pooling as a programmer is that there can be common global variables that once edited are available to all of the Forms runtime processes using that JVM. This means a value might get updated at the start of a trading day for example an Exchange Rate and that value until updated again is going to remain the same.  If the JVM is not started it should be dynamically started when the first Java call occurs.

As you can see there is justification for using JVM pooling for your system as it allows a reduction of resources to run users in your middleware applications and the global variable value allows sensible sharing of dynamic data.

Should you use it, I think it would be hard to justify not using it.

See ya round

Peter

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