Measuring CPU usage
per.liden at oracle.com
Wed Nov 28 08:38:17 UTC 2018
On 11/26/18 7:34 PM, Alex Elent wrote:
> I'm wondering if there are any flags we can pass to ZGC to capture total
> CPU used during GC in the GC logs.
> Looking for something similar to the "Real" metric that Parallel GC spits
> out. More specifically like this:
> [2018-11-26T16:50:42.793+0000][248690777ms] GC(8544) Pause Full
> (System.gc()) 6872M->757M(12169M) 1830.137ms
> [2018-11-26T16:50:42.793+0000][248690777ms] GC(8544) User=3.71s Sys=0.01s
We currently don't have that in ZGC. Are you looking for this
information for the pauses or for the complete GC cycle? Measuring this
on the process level for the complete cycle wouldn't make much sense, as
that would include time used by Java threads.
However, we do have plans to add CPU time in %, in addition to the wall
clock time, for both stw and concurrent phases. But that would then only
cover time spent by GC threads doing GC work. With this you could see if
a GC phase took a long time because a GC thread had a lot of work to do,
or because it didn't get (enough) time on the CPU.
> I'm currently using the following Xlog opts:
> Thank you kindly!
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