java - G1GC GC logs 是什么意思？

Question

我不明白 G1GC GC 日志的确切含义(添加 PrintGCDetails 和 PrintGCTimeStamps 时)。有人可以阐明语法吗？

[

GC pause (young), 0.03067078 secs]
   [SATB Drain Time:   0.2 ms]
   [Parallel Time:  22.6 ms]
      [GC Worker Start Time (ms):  165213430.0  165213430.0  165213430.0  165213430.0  165213430.0  165213430.0  165213430.1  165213430.1]
      [Update RS (ms):  10.7  10.0  11.1  9.9  9.9  11.2  10.6  8.6
       Avg:  10.3, Min:   8.6, Max:  11.2]
         [Processed Buffers : 14 8 8 12 9 11 10 8
          Sum: 80, Avg: 10, Min: 8, Max: 14]
      [Ext Root Scanning (ms):  2.5  2.6  2.9  3.4  3.3  2.7  2.6  2.4
       Avg:   2.8, Min:   2.4, Max:   3.4]
      [Mark Stack Scanning (ms):  0.0  0.0  0.0  0.0  0.0  0.0  0.0  2.2
       Avg:   0.3, Min:   0.0, Max:   2.2]
      [Scan RS (ms):  4.0  4.1  3.1  3.7  3.9  3.2  3.8  3.9
       Avg:   3.7, Min:   3.1, Max:   4.1]
      [Object Copy (ms):  4.7  5.3  4.7  4.8  4.7  4.7  4.8  4.7
       Avg:   4.8, Min:   4.7, Max:   5.3]
      [Termination (ms):  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0
       Avg:   0.0, Min:   0.0, Max:   0.0]
         [Termination Attempts : 23 1 26 23 19 29 22 25
          Sum: 168, Avg: 21, Min: 1, Max: 29]
      [GC Worker End Time (ms):  165213452.3  165213452.3  165213452.3  165213452.3  165213452.3  165213452.3  165213452.3  165213452.3]
      [Other:   0.7 ms]
   [Clear CT:   0.6 ms]
   [Other:   7.3 ms]
      [Choose CSet:   0.0 ms]
   [ 3329M->3245M(6000M)]

full GC 是什么意思？它是并行化的暂停吗？使用了哪种GC算法？为什么 G1 决定使用它？

5.941: [Full GC 7891K->4756K(6000M), 0.1939233 secs]

Answer 1

关于“它是并行化的暂停吗？”的信息很少用Java的话来说，GC 有两种类型(基于与 mutator 的并发性，即应用程序)- (1)Stop-the-world (2)Concurrent

Stop-the-world GC 进一步分割为 - 1a)如果 GC 线程数为一个则停止世界 1b)如果 GC 线程数多于一个则为并行