0 Replies Latest reply: Jan 3, 2013 10:57 AM by cscetbon RSS

    Full GC Time

    cscetbon
      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