James,
On 2/7/23 20:35, James H. H. Lampert wrote:
Monitored the thing all day, taking the CPU usage (via a WRKACTJOB) and
the current heap size and heap-in-use (via option 5 of a WRKJVMJOB)
every 15 minutes.
Heap size was 4925.375M (out of a maximum of 5120M) at 08:45, and the OS
took heap away over the course of the day, until it was down to 4352.0M
at 17:30. Heap in use fluctuated; from 11:45 to 13:00 it steadily
climbed from 2575.382M to 3668.079M, then by 13:30 it had dropped to
2169.834M. Job CPU hit 35.5% at 09:00; that was the highest I saw it all
day.
It would be unusual for the OS to reclaim any of that memory from the
JVM process. Are you looking at OS heap usage, or "JVM heap" usage? From
your description above, it's tough to tell. The tool is called WRKJVMJOB
so presumably it knows what the heck a JVM is, so maybe you were getting
the exact numbers I was recommending.
Are you able to graph them and eyeball the steady-state? What you
describe briefly seems healthy. Not sure about the 35% CPU usage; you
might just have witnessed a spike. Usually if the GC is thrashing,
you'll see a CPU pegged for a while.
That climb to 3668.079M peak (and I think it went higher, but not on the
quarter-hour) had me wondering if I was going to witness a crash.
... and did it crash? :)
-chris
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