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Mike Hanlon <mike.hanlon@hp.com>
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on 12 Jun 14
Configure JVM initial heap size
To enable some performance testing, this change will
allow configuration of JVM initial heap size. A new
env… Show more
Configure JVM initial heap size

To enable some performance testing, this change will

allow configuration of JVM initial heap size. A new

environment variable will be read when the instance

starts. The variable is named JVM_INIT_HEAP_SIZE_MB.

The unit is megabytes. Setting the variable to any

value above 0 will cause SQL set the initial heap size

for the JVM.

This change does not effect the setting of the JVM

maximum heap size. As before, the maximum is set to

a hard-coded default, currently 512MB, unless the

variable JVM_MAX_HEAP_SIZE_MB is set. Setting this

variable to zero has the effect of not configuring

any maximum.

In contrast, to avoid setting any value for the JVM

initial heap size, one can simply not define the

variable JVM_INIT_HEAP_SIZE.  The reason for this

inconsistency in how to use the variables is to

preserve default behavior.

So, for example, to setup the JVM to have no maximum

heap size, while having an initial heap size of 32MB,

one must set both variables, as shown here:

JVM_INIT_HEAP_SIZE_MB=32

JVM_MAX_HEAP_SIZE_MB=0

Change-Id: I4f503eda59f263a2762adb79b7d79ef158a3852a

Implements: blueprint jvm-inital-heap-config

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