G1 的 gc 日志 有点看不懂

Metaspace 的扩容 为什么会触发 global concurrent marking 这些操作又不会对 mataspace 产生影响

或者 Metadata GC Threshold 不是这个意思？？

2018-04-11T10:28:02.596+0800: 146329.480: [GC pause (Metadata GC Threshold) (young) (initial-mar), 0.0800508 secs] [Parallel Time: 75.5 ms, GC Workers: 4] [GC Worker Start (ms): Min: 146329484.8, Avg: 146329484.9, Max: 146329484.9, Diff: 0.1] [Ext Root Scanning (ms): Min: 11.2, Avg: 26.3, Max: 70.9, Diff: 59.6, Sum: 105.2] [Update RS (ms): Min: 0.0, Avg: 5.8, Max: 7.7, Diff: 7.7, Sum: 23.1] [Processed Buffers: Min: 0, Avg: 110.8, Max: 156, Diff: 156, Sum: 443] [Scan RS (ms): Min: 0.1, Avg: 0.1, Max: 0.1, Diff: 0.1, Sum: 0.5] [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.1] [Object Copy (ms): Min: 0.3, Avg: 25.6, Max: 34.2, Diff: 33.9, Sum: 102.5] [Termination (ms): Min: 0.0, Avg: 13.3, Max: 17.9, Diff: 17.9, Sum: 53.4] [Termination Attempts: Min: 1, Avg: 2.0, Max: 4, Diff: 3, Sum: 8] [GC Worker Other (ms): Min: 0.0, Avg: 0.1, Max: 0.2, Diff: 0.2, Sum: 0.4] [GC Worker Total (ms): Min: 71.2, Avg: 71.3, Max: 71.3, Diff: 0.1, Sum: 285.1] [GC Worker End (ms): Min: 146329556.1, Avg: 146329556.2, Max: 146329556.2, Diff: 0.0] [Code Root Fixup: 0.2 ms] [Code Root Purge: 0.0 ms] [Clear CT: 0.3 ms] [Other: 4.1 ms] [Choose CSet: 0.0 ms] [Ref Proc: 1.7 ms] [Ref Enq: 0.0 ms] [Redirty Cards: 0.1 ms] [Humongous Register: 0.0 ms] [Humongous Reclaim: 0.0 ms] [Free CSet: 0.5 ms] [Eden: 826.0M(2310.0M)->0.0B(2314.0M) Survivors: 92.0M->90.0M Heap: 2106.5M(4096.0M)->1281.7M(4096.0M)] [Times: user=0.29 sys=0.00, real=0.08 secs] 2018-04-11T10:28:02.677+0800: 146329.560: [GC concurrent-root-region-scan-start] 2018-04-11T10:28:02.677+0800: 146329.561: Total time for which application threads were stopped: 0.0831451 seconds, Stopping threads took: 0.0004791 seconds 2018-04-11T10:28:02.681+0800: 146329.565: Application time: 0.0041790 seconds