JVM data segment for NSJ 11

NSJ 11 allocates one extensible flat segment for its internal dynamic memory requirement. The initial size of this segment is 512 MB, and the maximum size is 12 GB. This segment is referred as JVM data segment.

NOTE:

The metaspace is allocated from JVM data segments.

When the allocated portion of the segment is filled, and if the allocated size of the segment has not reached the maximum value of 12 GB, then the segment is resized by increasing its size by multiples of 512 MB. To avoid segment resize during the application runtime NSJ provides an option InitialJVMHeapSize, that can be used to specify the maximum JVM heap size required by the application. If this option is specified during JVM initialization, the JVM heap segment is resized with the value specified and it avoids the resize of the JVM heap segment later when the application runs. It must be noted that the value specified with the command line option is a suggestive value. If the application needs more virtual memory, the segment can be resized until it reaches 12 GB. The syntax for this option is as follows:

–XX:InitialJVMHeapSize=<size>: where, size can vary from 512 MB to 12 GB. Default value of InitialJVMHeapSize is 512 MB.

Sample Invocation:

java –XX:InitialJVMHeapSize=4G <className>

In the sample command invocation, during JVM initialization, the JVM Heap segment is resized to 4 GB.

NOTE:

Minimum size of the JVM heap segment cannot be less than 512 MB.