RFR: Record Shenandoah events in hs_err events section + capture degen GC in status line

[Roman Kennke]

Looks good to me

On Thu, Feb 22, 2018 at 6:59 PM, Aleksey Shipilev <shade at redhat.com> wrote:
> http://cr.openjdk.java.net/~shade/shenandoah/hserr-events/webrev.01/
>
> This improves hs_err that we get during the errors, in two ways:
>  rev 49078 : Capture degenerated GC in hs_err status line
>  rev 49079 : Record Shenandoah events in hs_err events section
>
> The code could be a little better, if we ever used the *Mark object, but it is not very easy to do,
> because GCTraceTime is actually the macro-definition, not the class. Something to clean up later.
>
> Excerpt from the artificially induced hs_err is below. It basically allows to reconstruct the entire
> GC cycle without having the GC log:
>
> ---- 8< -------------------------------------------------------------------------------------
>
> Status: marking, degenerated gc, conc gc cancelled
>
> ...
>
> Events (250 events):
> ...
> Event: 0.922 Executing VM operation: ShenandoahInitMark
> Event: 0.923 Pause Init Mark
> Event: 0.931 Pause Init Mark done
> Event: 0.931 Executing VM operation: ShenandoahInitMark done
> Event: 0.931 Concurrent marking
> Event: 0.934 Concurrent marking done
> Event: 0.934 Executing VM operation: ShenandoahFinalMarkStartEvac
> Event: 0.953 Pause Final Mark
> Event: 0.965 Pause Final Mark done
> Event: 0.965 Executing VM operation: ShenandoahFinalMarkStartEvac done
> Event: 0.965 Concurrent cleanup
> Event: 0.975 Concurrent cleanup done
> Event: 0.975 Concurrent cleanup
> Event: 0.984 Concurrent cleanup done
> Event: 0.994 Executing VM operation: ShenandoahInitMark
> Event: 0.994 Pause Init Mark
> Event: 1.003 Pause Init Mark done
> Event: 1.003 Executing VM operation: ShenandoahInitMark done
> Event: 1.003 Concurrent marking (unload classes)
> Event: 1.006 Thread 0x000015307c439000 Cancelling concurrent GC: Allocation Failure
> Event: 1.007 Concurrent marking (unload classes) done
> Event: 1.020 Executing VM operation: ShenandoahDegeneratedGC
> Event: 1.020 Pause Degenerated GC (Mark)
> ---- 8< -------------------------------------------------------------------------------------
>
> Testing: hotspot_gc_shenandoah
>
> Thanks,
> -Aleksey
>