Can anyone comment on the following verbosegc lines in a Java runtime with CMS GC enabled? In particular:
- Does the event indicate the
29.490location of a heap of water for labeling? - What is a phase
precleanand how does it differ from labeling? - What is a phase
reset? Why does it take time to complete if it is not just the end of a sweep? - Finally, what is
Rescan, greyand rootrescans and remarkarea metrics and events 29.653? Should we assume that these are just the reported heap metrics for later sweep? If so, why do they consume time?
verbosegc log excerpt:
29.490: [GC [1 CMS-initial-mark: 16225K(17684K)] 16737K(22420K), 0.0030839 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
29.494: [CMS-concurrent-mark-start]
29.652: [CMS-concurrent-mark: 0.158/0.158 secs] [Times: user=0.16 sys=0.00, real=0.16 secs]
29.652: [CMS-concurrent-preclean-start]
29.652: [CMS-concurrent-preclean: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
29.653: [GC[YG occupancy: 512 K (4736 K)]29.653: [Rescan (non-parallel) 29.654: [grey object rescan, 0.0001517 secs]29.654: [root rescan, 0.0030887 secs], 0.0033817 secs]29.657: [weak refs processing, 0.0000271 secs] [1 CMS-remark: 16225K(17684K)] 16737K(22420K), 0.0035183 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
29.658: [CMS-concurrent-sweep-start]
29.679: [CMS-concurrent-sweep: 0.022/0.022 secs] [Times: user=0.03 sys=0.00, real=0.03 secs]
29.680: [CMS-concurrent-reset-start]
29.703: [CMS-concurrent-reset: 0.022/0.022 secs] [Times: user=0.02 sys=0.00, real=0.01 secs]
29.797: [GC 29.797: [DefNew: 4736K->512K(4736K), 0.0207183 secs] 20800K->17172K(31512K), 0.0209119 secs] [Times: user=0.01 sys=0.02, real=0.03 secs]
Thanks,