Question

我在Hotspot JVM上运行Java 7 update 45上的应用程序。我试图调整参数以适应低延迟应用程序，下面是我为此次运行设置的JVM参数。 GC日志中各个步骤的时间（约25ms）不等于暂停时间（> 600ms）。我怎么知道是什么导致这个暂停时间如此之高？在大多数收藏中，他们加起来很好，并且在暂停时间目标中。我偶尔会看到如此大的停顿，一次在15-20分钟左右（虽然不是那么规律）。

-server -Xmx2g -Xms2g -XX：PermSize = 128m -XX：MaxPermSize = 128m -XX：+ UseG1GC -XX：MaxGCPauseMillis = 30 -XX：ParallelGCThreads = 9 -XX：ConcGCThreads = 4 -XX：G1HeapRegionSize = 4M -XX：InitiatingHeapOccupancyPercent = 45 -XX：+ PrintTLAB -XX：+ AggressiveOpts -Xloggc：/integral/logs/gc.log -verbose：gc -XX：+ PrintTenuringDistribution -XX：+ PrintGCDateStamps -XX：+ PrintAdaptiveSizePolicy -XX：+ PrintGCDetails -XX：+ PrintGCApplicationConcurrentTime -XX：+ PrintGCApplicationStoppedTime -XX：+ PrintSafepointStatistics -XX：PrintSafepointStatisticsCount = 1 -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port = 3026 -Dcom.sun.management.jmxremote .local.only = false -Dcom.sun.management.jmxremote.authenticate = false -Dcom.sun.management.jmxremote.ssl = false“

2014-01-28T16:16:12.084+0000: 27507.054: Application time: 8.9506630 seconds
2014-01-28T16:16:12.084+0000: 27507.055: [GC pause (young)
Desired survivor size 81788928 bytes, new threshold 15 (max 15)
- age   1:    2299088 bytes,    2299088 total
- age   2:    1732832 bytes,    4031920 total
- age   3:    1748064 bytes,    5779984 total
- age   4:    1709368 bytes,    7489352 total
- age   5:    1732360 bytes,    9221712 total
- age   6:    1722776 bytes,   10944488 total
- age   7:    1712168 bytes,   12656656 total
- age   8:    1706240 bytes,   14362896 total
- age   9:    1692040 bytes,   16054936 total
- age  10:    1736008 bytes,   17790944 total
- age  11:    1566384 bytes,   19357328 total
- age  12:    1508456 bytes,   20865784 total
- age  13:    1491480 bytes,   22357264 total
- age  14:    1652136 bytes,   24009400 total
- age  15:    1502120 bytes,   25511520 total
 27507.055: [G1Ergonomics (CSet Construction) start choosing CSet, _pending_cards: 12464, predicted base time: 7.97 ms, remaining time: 22.03 ms, target pause time: 30.00 ms]
 27507.055: [G1Ergonomics (CSet Construction) add young regions to CSet, eden: 298 regions, survivors: 9 regions, predicted young region time: 12.39 ms]
 27507.055: [G1Ergonomics (CSet Construction) finish choosing CSet, eden: 298 regions, survivors: 9 regions, old: 0 regions, predicted pause time: 20.36 ms, target pause time: 30.00 ms]
, 0.0236600 secs]
   [Parallel Time: 22.0 ms, GC Workers: 9]
      [GC Worker Start (ms): Min: 27507055.7, Avg: 27507057.0, Max: 27507058.7, Diff: 3.1]
      [Ext Root Scanning (ms): Min: 2.1, Avg: 3.8, Max: 5.2, Diff: 3.1, Sum: 34.4]
      [Update RS (ms): Min: 1.9, Avg: 2.3, Max: 3.0, Diff: 1.1, Sum: 20.8]
         [Processed Buffers: Min: 4, Avg: 11.7, Max: 23, Diff: 19, Sum: 105]
      [Scan RS (ms): Min: 0.0, Avg: 0.1, Max: 0.2, Diff: 0.2, Sum: 1.2]
      [Object Copy (ms): Min: 12.9, Avg: 13.1, Max: 13.3, Diff: 0.3, Sum: 117.6]
      [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
      [GC Worker Other (ms): Min: 0.0, Avg: 0.5, Max: 0.8, Diff: 0.8, Sum: 4.8]
      [GC Worker Total (ms): Min: 17.7, Avg: 19.9, Max: 21.5, Diff: 3.8, Sum: 178.8]
      [GC Worker End (ms): Min: 27507076.4, Avg: 27507076.9, Max: 27507077.2, Diff: 0.8]
   [Code Root Fixup: 0.0 ms]
   [Clear CT: 0.3 ms]
   [Other: 1.3 ms]
      [Choose CSet: 0.0 ms]
      [Ref Proc: 0.3 ms]
      [Ref Enq: 0.0 ms]
      [Free CSet: 0.6 ms]
   [Eden: 1192.0M(1192.0M)->0.0B(1192.0M) Survivors: 36.0M->36.0M Heap: 1796.8M(2048.0M)->605.0M(2048.0M)]
 [Times: user=0.17 sys=0.00, real=0.64 secs] 
2014-01-28T16:16:12.719+0000: 27507.690: Total time for which application threads were stopped: 0.6354760 seconds

G1垃圾收集器调整

0 个答案: