java GC日志該怎么看？

問題描述

{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: [ParNewDesired 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)}

上面是我的一個GC日志，我想問這種日志該怎么看呢？之前只是學過一些理論的東西，頭一次接觸真正的GC日志

問題解答

可以看看深入理解java虛擬機... 里面有講解..

如何查看jvm 的gc 日志，雖然有點老了，但是很有借鑒意義 http://www.inter12.org/archiv...

1、數字“11.569：”代表了GC發生的時間，這個數字的含義是從Java虛擬機啟動以來經過的秒數。2、[ParNew表示GC發生的區域，這里的顯示跟GC收集器類型有關，這里表示用ParNew收集器3、859714K->96106K(917504K), 0.0484250 secs，表示GC前該內存區域已經使用的容量-->GC后該內存區域使用容量(該內存區域總容量)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堆總容量)，該內存區域GC所占用的時間。5、[Times: user=0.19 sys=0.00, real=0.05 secs]表示程序耗時、系統耗時、實際耗時。這里user的時間超過real的時間，這是正常的，表示是多線程進行CPU切換，疊加了多線程的時間。