Full GC Time

Question

Hi,
I'm trying to find How to monitor the Full GC Time (or the real GC Time) of my java process with JMX. when I try with Jconsole, I see that GC Time (in my case) is composed of ParNew Time (young) and CMS Time (tenured???) as follows :
GC time: 
10.328 seconds on ParNew (261 collections)
00.231 seconds on ConcurrentMarkSweep (4 collections)
But when I launch a gc() with the Jconsole, I see in my process log (my host was busy) :
[Full GC 323515K->61542K(1028096K), 9.6899086 secs] , yes 9.7 seconds !!
why I do not see more seconds for the CMS in the Jconsole after that ?
GC time: 
10.328 seconds on ParNew (261 collections)
00.235 seconds on ConcurrentMarkSweep (6 collections) <-- only 235ms
is it real time in one case (Jconsole) and CPU time in the process log ?
I tried with jstat and it returns the good value in GCT (FGCT + YGCT) :
S0 S1 E O P YGC YGCT FGC FGCT GCT
0.00 0.00 6.97 7.29 59.95 261 10.331 6 10.381 20.712
thanks

Answer 1

Hi,
Try to experiment with the XX:MaxNewSize=356m, -XX:NewSize.
Or -Xmn.
It may work again with 1.4.1.X.
I have problems with this in the higher versions
of 1.3.1_XX but it helped with the older versions
a lot.
andreas