G1GC不自动调整NewSize（长GC时间）

时间：2018-02-27 04:53:42

标签： java garbage-collection jvm heap-memory g1gc

我的应用程序是G1GC，内存大小为45GB。我看到很长的GC时间。在进行调查时，我发现只有5％的年轻一代的堆正常被填满而导致频繁收集。此外，尽管大多数堆都是空的，但GC并没有调整＆＃34; NewSize＆＃34;并且它恒定为5％，并且大部分堆被保留（但未使用）用于＆＃34; Tenured Generation＆＃34;。 G1GC文档表明，每次GC收集时都会自动调整NewSize。

https://docs.oracle.com/javase/9/gctuning/garbage-first-garbage-collector.htm#JSGCT-GUID-C268549C-7D95-499C-9B24-A6670B44E49C

问题： -

  1. ＆＃34; G1MaxNewSizePercent＆＃34;的默认值和G1NewSizePercent分别为60％和5％，为什么GC没有自动调整大小，为什么它停留在5％。 http://www.oracle.com/technetwork/articles/java/g1gc-1984535.html
  2. 我是否需要为GC开始自动调整？
  3. 为什么大部分堆首先为终身代保留？

    4. 以下是GCViewer快照

    GC viewer

    JVM标志

    sudo -u ./jcmd [PID] VM.flags

-XX:+AlwaysPreTouch
-XX:CICompilerCount=15 
-XX:ConcGCThreads=6 
-XX:G1HeapRegionSize=16777216 
-XX:GCLogFileSize=10485760 
-XX:+HeapDumpOnOutOfMemoryError 
-XX:InitialHeapSize=48318382080 
-XX:MarkStackSize=4194304 
-XX:MaxHeapSize=48318382080 
-XX:MaxNewSize=28991029248 
-XX:MinHeapDeltaBytes=16777216 
-XX:NumberOfGCLogFiles=5 
-XX:-OmitStackTraceInFastThrow 
-XX:OnOutOfMemoryError=/bin/kill -9 %p 
-XX:+PrintGC -XX:+PrintGCApplicationStoppedTime 
-XX:+PrintGCDateStamps 
-XX:+PrintGCDetails 
-XX:+PrintGCTimeStamps 
-XX:+PrintTenuringDistribution 
-XX:+UseG1GC 
-XX:+UseGCLogFileRotation

    GC LOG快照

         2018-02-26T21:44:51.808+0000: 3964500.472: Total time for which application threads were stopped: 1.6367601 seconds, Stopping threads took: 0.0013929 seconds
2018-02-26T21:45:30.402+0000: 3964539.066: [GC pause (G1 Evacuation Pause) (young)
Desired survivor size 150994944 bytes, new threshold 15 (max 15)
- age   1:    9990048 bytes,    9990048 total
- age   2:    3134528 bytes,   13124576 total
- age   3:    3096528 bytes,   16221104 total
- age   4:    3214512 bytes,   19435616 total
- age   5:    1927232 bytes,   21362848 total
- age   6:    1268760 bytes,   22631608 total
- age   7:     717648 bytes,   23349256 total
- age   8:     439232 bytes,   23788488 total
- age   9:     246680 bytes,   24035168 total
- age  10:     167256 bytes,   24202424 total
- age  11:      49928 bytes,   24252352 total
- age  12:      54232 bytes,   24306584 total
- age  13:      58920 bytes,   24365504 total
- age  14:      56704 bytes,   24422208 total
- age  15:      43744 bytes,   24465952 total
, 1.5579128 secs]
   [Parallel Time: 34.2 ms, GC Workers: 25]
      [GC Worker Start (ms): Min: 3964539071.6, Avg: 3964539071.9, Max: 3964539072.2, Diff: 0.6]
      [Ext Root Scanning (ms): Min: 9.4, Avg: 11.8, Max: 14.3, Diff: 4.9, Sum: 294.7]
      [Update RS (ms): Min: 6.1, Avg: 9.8, Max: 19.2, Diff: 13.1, Sum: 245.1]
         [Processed Buffers: Min: 14, Avg: 162.4, Max: 668, Diff: 654, Sum: 4059]
      [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.3]
      [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
      [Object Copy (ms): Min: 2.3, Avg: 9.4, Max: 11.7, Diff: 9.4, Sum: 235.3]
      [Termination (ms): Min: 1.0, Avg: 2.4, Max: 4.3, Diff: 3.3, Sum: 60.0]
         [Termination Attempts: Min: 78, Avg: 230.8, Max: 303, Diff: 225, Sum: 5769]
      [GC Worker Other (ms): Min: 0.1, Avg: 0.1, Max: 0.3, Diff: 0.2, Sum: 3.6]
      [GC Worker Total (ms): Min: 33.2, Avg: 33.6, Max: 33.9, Diff: 0.7, Sum: 839.0]
      [GC Worker End (ms): Min: 3964539105.5, Avg: 3964539105.5, Max: 3964539105.6, Diff: 0.1]
   [Code Root Fixup: 0.1 ms]
   [Code Root Purge: 0.0 ms]
   [Clear CT: 0.7 ms]
   [Other: 1522.9 ms]
      [Choose CSet: 0.0 ms]
      [Ref Proc: 1510.4 ms]
      [Ref Enq: 0.1 ms]
      [Redirty Cards: 0.4 ms]
      [Humongous Register: 0.1 ms]
      [Humongous Reclaim: 0.0 ms]
      [Free CSet: 0.5 ms]
   [Eden: 2256.0M(2256.0M)->0.0B(2256.0M) Survivors: 48.0M->48.0M Heap: 5703.0M(45.0G)->3449.3M(45.0G)]
 [Times: user=1.62 sys=0.34, real=1.56 secs]
2018-02-26T21:45:31.963+0000: 3964540.627: Total time for which application threads were stopped: 1.5935495 seconds, Stopping threads took: 0.0057849 seconds
2018-02-26T21:45:40.547+0000: 3964549.211: Total time for which application threads were stopped: 0.0743828 seconds, Stopping threads took: 0.0024422 seconds
2018-02-26T21:45:51.083+0000: 3964559.748: Total time for which application threads were stopped: 0.0173656 seconds, Stopping threads took: 0.0011296 seconds
2018-02-26T21:46:06.646+0000: 3964575.310: [GC pause (G1 Evacuation Pause) (young)
Desired survivor size 150994944 bytes, new threshold 15 (max 15)
- age   1:   10282952 bytes,   10282952 total
- age   2:    3420512 bytes,   13703464 total
- age   3:    2663240 bytes,   16366704 total
- age   4:    2506952 bytes,   18873656 total
- age   5:    1215280 bytes,   20088936 total
- age   6:     555136 bytes,   20644072 total
- age   7:     542128 bytes,   21186200 total
- age   8:     336520 bytes,   21522720 total
- age   9:     173096 bytes,   21695816 total
- age  10:     117656 bytes,   21813472 total
- age  11:      44280 bytes,   21857752 total
- age  12:      45728 bytes,   21903480 total
- age  13:      53928 bytes,   21957408 total
- age  14:      58128 bytes,   22015536 total
- age  15:      56704 bytes,   22072240 total
, 1.2324057 secs]
   [Parallel Time: 39.1 ms, GC Workers: 25]
      [GC Worker Start (ms): Min: 3964575316.2, Avg: 3964575317.5, Max: 3964575318.7, Diff: 2.4]
      [Ext Root Scanning (ms): Min: 9.0, Avg: 12.4, Max: 16.1, Diff: 7.0, Sum: 311.0]
      [Update RS (ms): Min: 2.1, Avg: 8.2, Max: 16.4, Diff: 14.3, Sum: 206.0]
         [Processed Buffers: Min: 24, Avg: 149.3, Max: 246, Diff: 222, Sum: 3732]
      [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.4]
      [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]
      [Object Copy (ms): Min: 6.9, Avg: 12.5, Max: 15.5, Diff: 8.6, Sum: 311.5]
      [Termination (ms): Min: 2.6, Avg: 3.9, Max: 4.7, Diff: 2.1, Sum: 96.9]
         [Termination Attempts: Min: 179, Avg: 384.9, Max: 448, Diff: 269, Sum: 9622]
      [GC Worker Other (ms): Min: 0.0, Avg: 0.5, Max: 0.7, Diff: 0.7, Sum: 12.4]
      [GC Worker Total (ms): Min: 36.3, Avg: 37.5, Max: 38.7, Diff: 2.4, Sum: 938.3]
      [GC Worker End (ms): Min: 3964575354.9, Avg: 3964575355.0, Max: 3964575355.1, Diff: 0.1]
   [Code Root Fixup: 0.1 ms]
   [Code Root Purge: 0.0 ms]
   [Clear CT: 0.6 ms]
   [Other: 1192.6 ms]
      [Choose CSet: 0.0 ms]
      [Ref Proc: 1180.2 ms]
      [Ref Enq: 0.1 ms]
      [Redirty Cards: 0.4 ms]
      [Humongous Register: 1.8 ms]
      [Humongous Reclaim: 0.0 ms]
      [Free CSet: 0.3 ms]
   [Eden: 2256.0M(2256.0M)->0.0B(2256.0M) Survivors: 48.0M->48.0M Heap: 5705.3M(45.0G)->3439.2M(45.0G)]
 [Times: user=1.86 sys=0.00, real=1.23 secs]
2018-02-26T21:46:07.880+0000: 3964576.545: Total time for which application threads were stopped: 1.2492396 seconds, Stopping threads took: 0.0013324 seconds
2018-02-26T21:46:41.430+0000: 3964610.095: Total time for which application threads were stopped: 0.0331942 seconds, Stopping threads took: 0.0043586 seconds
2018-02-26T21:46:44.246+0000: 3964612.910: [GC pause (G1 Evacuation Pause) (young)

0 个答案:

没有答案
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