Measuring STW Pauses

Alex Elent alex at
Tue Nov 20 23:52:06 UTC 2018


I read through JEP 333 and it looks incredibly promising. My question is,
how does one measure the STW pauses in ZGC?

I read through the mailing list archives and understand there are 3 pauses:
Pause Mark Start
Pause Mark End
Pause Relocate Start

Using the below snippet of gc log:
[2018-11-20T23:34:46.180+0000][5135ms] GC(1) *Pause Mark Start 4.975ms*
[2018-11-20T23:34:46.301+0000][5256ms] GC(1) Concurrent Mark 120.118ms
[2018-11-20T23:34:46.301+0000][5256ms] GC(1) *Pause Mark End 0.684ms*
[2018-11-20T23:34:46.304+0000][5259ms] GC(1) Concurrent Process Non-Strong
References 2.308ms
[2018-11-20T23:34:46.304+0000][5259ms] GC(1) Concurrent Reset Relocation
Set 0.008ms
[2018-11-20T23:34:46.304+0000][5259ms] GC(1) Concurrent Destroy Detached
Pages 0.001ms
[2018-11-20T23:34:46.305+0000][5260ms] GC(1) Concurrent Select Relocation
Set 1.072ms
[2018-11-20T23:34:46.306+0000][5261ms] GC(1) Concurrent Prepare Relocation
Set 1.078ms
[2018-11-20T23:34:46.310+0000][5265ms] GC(1) *Pause Relocate Start 3.764ms*

Does that mean the STW pause for that cycle was 4.975 + 0.684 + 3.764

Thanks in advance,

More information about the zgc-dev mailing list