JDK-6291341 : jstat: FGC counter confusing when CMS GC is used
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 5.0
  • Priority: P3
  • Status: Closed
  • Resolution: Cannot Reproduce
  • OS: generic
  • CPU: generic
  • Submitted: 2005-06-27
  • Updated: 2024-10-07
  • Resolved: 2013-04-29
Related Reports
Relates :  
JDK-7072527 - CMS: JMM GC counters overcount in some cases
Relates :  
JDK-6580448 - CMS: Full GC collection count mismatch between GarbageCollectorMXBean and jvmstat (VisualGC)
Relates :  
JDK-8151674 - STW phases at Concurrent GC should count in PerfCounter
Description
When you look at the jstat -gc counters of a process running the
CMS collector, it appears as though each CMS collection cycle
increments the FGC counter by 2, instead of the expected 1.
This can be confusing and should be fixed.
###@###.### 2005-06-27 22:26:08 GMT
Comments
Today, I tried to reproduce the bug but it didn't come up in jdk5 (version 1.5.0_01), jdk7 (version 1.7.0_04) and jdk8. I will close it as "Cannot reproduce". *The bug may have been fixed somewhere, which could be as early as in JDK5.
29-04-2013
EVALUATION Cause known and will be addressed in Dolphin.
20-06-2006
SUGGESTED FIX As far as i know the collectors do not, as of today, export any specific collections_completed counters, being a count of the number of _actual_ collections (of a given type) in a run. Perhaps they should, and those are the values to display via jstat? ###@###.### 2005-06-27 22:26:08 GMT
27-06-2005