In our application, we use G1 gc. We have received the following log:
2022-11-04T16:51:02.322+0800: 4923545.042: [GC pause (G1 Evacuation Pause) (young), 0.1095177 secs]
[Parallel Time: 106.2 ms, GC Workers: 5]
[GC Worker Start (ms): Min: 4923545042.9, Avg: 4923545042.9, Max: 4923545042.9, Diff: 0.0]
[Ext Root Scanning (ms): Min: 2.1, Avg: 2.9, Max: 4.5, Diff: 2.5, Sum: 14.5]
[Update RS (ms): Min: 4.5, Avg: 5.9, Max: 6.6, Diff: 2.2, Sum: 29.4]
[Processed Buffers: Min: 68, Avg: 90.6, Max: 115, Diff: 47, Sum: 453]
[Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.1]
[Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
[Object Copy (ms): Min: 97.1, Avg: 97.3, Max: 97.4, Diff: 0.4, Sum: 486.4]
[Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
[Termination Attempts: Min: 1, Avg: 15.2, Max: 23, Diff: 22, Sum: 76]
[GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.0, Sum: 0.2]
[GC Worker Total (ms): Min: 106.1, Avg: 106.1, Max: 106.2, Diff: 0.0, Sum: 530.7]
[GC Worker End (ms): Min: 4923545149.0, Avg: 4923545149.0, Max: 4923545149.1, Diff: 0.0]
[Code Root Fixup: 0.0 ms]
[Code Root Purge: 0.0 ms]
[Clear CT: 0.3 ms]
[Other: 2.9 ms]
[Choose CSet: 0.0 ms]
[Ref Proc: 0.6 ms]
[Ref Enq: 0.0 ms]
[Redirty Cards: 0.4 ms]
[Humongous Register: 0.1 ms]
[Humongous Reclaim: 0.0 ms]
[Free CSet: 0.3 ms]
[Eden: 3808.0M(3808.0M)->0.0B(4928.0M) Survivors: 480.0M->352.0M Heap: 30.2G(84.0G)->26.5G(84.0G)]
[Times: user=0.55 sys=0.00, real=39.57 secs]
As described in the article: Collecting and reading G1 garbage collector logs - part 2 , the collection time is 0.1095177 secs
2022-11-04T16:51:02.322+0800: 4923545.042: [GC pause (G1 Evacuation Pause) (young), 0.1095177 secs]
But the real time (39.57 secs) is larger than the sum of the others (user + sys).
[Times: user=0.55 sys=0.00, real=39.57 secs]
So which is the STW time for this young-only collection? The collection time or the real time?
In the article, the reason for the condition when real time is greater than user + sys times:
In certain circumstances, you might see real time to be greater than user + sys time. If it happens often and the differences are substantial, then it might mean that there is either a lack of CPU or there is heavy I/O activity in the system.
I have checked the cpu and internet I/O, they are all right. I hava no idea why the real time is greater than other times.
Which is STW time? And why the real time is greater than other times?
