Heap monitor default operation

The heap monitor follows default operation behavior as described in this file.

An active heap monitor typically sends a message to the QSYSOPR message queue when the WebSphere® Application Server profile starts. For example, the Display Message command (DSPMSG QSYSOPR) displays the following message:

HEAP MONITOR STARTED FOR 012500/QEJBSVR/SERVER1 IN SUBSYSTEM qwas85 IN POOL
  *BASE POOL ID=2 POOLSIZE(B)=1687994368 RESERVED(B)=778240 HEAP
  TOTAL(B)=202276864 FREE(B)=67037600 USEDHEAP=135239264
  OS400.GC.HEAP.SIZE.MAX(KB)  =240000000

In default operation, a similar message displays ENDED instead of STARTED when the WebSphere Application Server profile is ended. For example:

HEAP MONITOR ENDED FOR 012500/QEJBSVR/SERVER1 IN SUBSYSTEM
 qwas85 IN POOL *BASE POOL ID=2 POOLSIZE(B)=6662139904 RESERVED(B)=5165056
 HEAP TOTAL(B)=312999936 FREE(B)=168637264 USEDHEAP=144362672
 OS400.GC.HEAP.SIZE.MAX(KB)  =240000000

The Display Log command (DSPLOG LOG(QHST) MSGID(CPI8859)) shows all STARTED and ENDED messages in the history log.

The default operation monitors the size of the Java™ virtual machine (JVM) Garbage Collection (GC) heap against the following:

The size of the effective memory pool.
The size of the memory pool size minus the reserved size.

It also issues a message if the effective memory pool size exceeds 85, 90, 95, or 100 percent. For example:

048241/QEJBSVR/SERVER1 GC HEAP USES 95% OF THE NON-RESERVED POOL.  JVM GC
   HEAP SIZE(KB)  EFFECTIVE POOLSIZE(KB):840282 882444.
 048241/QEJBSVR/SERVER1 GC HEAP USES 110% OF THE NON-RESERVED POOL.  JVM GC
   HEAP SIZE(KB)  EFFECTIVE POOLSIZE(KB):974601 882392.

The first number is the size of the heap, such as 840282 or 974601. The second number is the effective pool size (or non-reserved pool size), such as 882444 or 882392. The Display Log command (DSPLOG LOG(QHST) MSGID(CPF9898)) shows warning messages in the history log.

For the maximum Garbage Collection heap size, the default operation is to monitor the size of the JVM Garbage Collection heap so that it does not exceed 85, 90, or 95 percent of the maximum. For example:

048358/QEJBSVR/USER JAVA USED 88% OF THE GC HEAP.  USED HEAP SIZE(KB)
  AND MAX HEAP(KB):909088 1024001.

The maximum heap size is 1024001 Kbytes (-Xmx1000m), and the used heap size is 909088 Kbytes.