java GC日志该怎么看？

Question

{Heap before GC invocations=70426 (full 39):
 par new generation   total 917504K, used 849770K [0x0000000730000000, 0x0000000770000000, 0x0000000770000000)
  eden space 786432K, 100% used [0x0000000730000000, 0x0000000760000000, 0x0000000760000000)
  from space 131072K,  48% used [0x0000000760000000, 0x0000000763dda9d8, 0x0000000768000000)
  to   space 131072K,   0% used [0x0000000768000000, 0x0000000768000000, 0x0000000770000000)
 concurrent mark-sweep generation total 1050496K, used 735717K [0x0000000770000000, 0x00000007b01e0000, 0x00000007f0000000)
 concurrent-mark-sweep perm gen total 262144K, used 44072K [0x00000007f0000000, 0x0000000800000000, 0x0000000800000000)
2017-03-11T17:52:34.524+0800: 86930.373: [GC2017-03-11T17:52:34.524+0800: 86930.373: [ParNew
Desired survivor size 67108864 bytes, new threshold 15 (max 15)
- age   1:    7498968 bytes,    7498968 total
- age   2:   10419016 bytes,   17917984 total
- age   3:    9045656 bytes,   26963640 total
- age   4:    3149912 bytes,   30113552 total
- age   5:    1557968 bytes,   31671520 total
- age   6:    1181200 bytes,   32852720 total
- age   7:     900696 bytes,   33753416 total
- age   8:    1135200 bytes,   34888616 total
- age   9:    1545448 bytes,   36434064 total
- age  10:    1038000 bytes,   37472064 total
- age  11:    1199288 bytes,   38671352 total
- age  12:     840296 bytes,   39511648 total
- age  13:    1264520 bytes,   40776168 total
- age  14:    1005752 bytes,   41781920 total
- age  15:    1008152 bytes,   42790072 total
: 849770K->62511K(917504K), 0.0296150 secs] 1585488K->798923K(1968000K), 0.0299000 secs] [Times: user=0.11 sys=0.00, real=0.03 secs]
Heap after GC invocations=70427 (full 39):
 par new generation   total 917504K, used 62511K [0x0000000730000000, 0x0000000770000000, 0x0000000770000000)
  eden space 786432K,   0% used [0x0000000730000000, 0x0000000730000000, 0x0000000760000000)
  from space 131072K,  47% used [0x0000000768000000, 0x000000076bd0bf30, 0x0000000770000000)
  to   space 131072K,   0% used [0x0000000760000000, 0x0000000760000000, 0x0000000768000000)
 concurrent mark-sweep generation total 1050496K, used 736411K [0x0000000770000000, 0x00000007b01e0000, 0x00000007f0000000)
 concurrent-mark-sweep perm gen total 262144K, used 44072K [0x00000007f0000000, 0x0000000800000000, 0x0000000800000000)
}

上面是我的一个GC日志，我想问这种日志该怎么看呢？之前只是学过一些理论的东西，头一次接触真正的GC日志

Answer 1

可以看看深入理解java虚拟机... 里面有讲解..

Answer 2

如何查看jvm 的gc 日志，虽然有点老了，但是很有借鉴意义 http://www.inter12.org/archiv...

Answer 3

1、数字“11.569：”代表了GC发生的时间，这个数字的含义是从Java虚拟机启动以来经过的秒数。
2、[ParNew表示GC发生的区域，这里的显示跟GC收集器类型有关，这里表示用ParNew收集器
3、859714K->96106K(917504K), 0.0484250 secs，表示GC前该内存区域已经使用的容量-->GC后该内存区域使用容量(该内存区域总容量)
4、859714K->96106K(1966080K), 0.0486090 secs，表示GC前java堆已使用容量-->GC后java堆已使用容量(Java堆总容量)，该内存区域GC所占用的时间。
5、[Times: user=0.19 sys=0.00, real=0.05 secs]表示程序耗时、系统耗时、实际耗时。这里user的时间超过real的时间，这是正常的，表示是多线程进行CPU切换，叠加了多线程的时间。