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: