In JDK-8240239 we replaced the ConcurrentGCPhaseManager with a different more generically applicable mechanism.

This change added a few log messages that after some further testing were found to be non-optimal. Here are some of them:

[4.519s][info ][gc,cpu ] GC(12) User=0.89s Sys=0.00s Real=0.05s
[4.519s][debug][gc,breakpoint ] Now active
[4.519s][info ][gc ] GC(13) Concurrent Cycle

and later

5.104s][debug][gc,breakpoint ] Now idle
[5.104s][info ][gc ] GC(13) Concurrent Cycle 584.964ms

These "Now idle" and "Now active" messages seem to be superfluous in context; there is some "Now idle" that reports reaching idle instead of the requested breakpoint.

That one should probably be improved, and the others could be removed.

Further, these messages should be associated with the current GC cycle (e.g. in this case, add a "GC(13)" prefix).

Other gc,breakpoint messages should probably be either removed or relegated to trace messages, as they mostly serve for implmentation debugging purposes not really ready for an end user. Or maybe removed too.