JVM相关命令

发表于 更新于 分类于 阅读次数： Waline：

查看JVM相关的信息。

jinfo [option] <pid>

查看JVM使用的哪个垃圾回收器

jinfo -flags <pid>

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# jinfo -flags 58256
Attaching to process ID 58256, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.212-b10
Non-default VM flags: -XX:CICompilerCount=4 -XX:InitialHeapSize=264241152 -XX:MaxHeapSize=4200595456
 -XX:MaxNewSize=1399848960 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=88080384 -XX:OldSize=176160768
  -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC

可以看出是使用的 UseParallelGC。

通过如下命令也可以印证。

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# jinfo -flag UseParallelGC 58256
-XX:+UseParallelGC

查看类加载的信息

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# jstat -class 58256 1000 10
Loaded  Bytes  Unloaded  Bytes     Time
 14582 26192.0        1     0.9      23.92
 14582 26192.0        1     0.9      23.92
 14582 26192.0        1     0.9      23.92
 14582 26192.0        1     0.9      23.92
 14582 26192.0        1     0.9      23.92
 14582 26192.0        1     0.9      23.92
 14582 26192.0        1     0.9      23.92

查看垃圾回收器的信息

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# jstat -gc 58256 1000 10
 S0C    S1C    S0U    S1U      EC       EU        OC         OU       MC     MU    CCSC   CCSU   YGC     YGCT    FGC    FGCT     GCT
28160.0 10240.0  0.0   9808.1 597504.0 430347.2  251904.0   69700.9   78612.0 74904.0 10300.0 9577.3     17    0.643   3      1.166    1.809
28160.0 10240.0  0.0   9808.1 597504.0 430347.2  251904.0   69700.9   78612.0 74904.0 10300.0 9577.3     17    0.643   3      1.166    1.809
28160.0 10240.0  0.0   9808.1 597504.0 430347.2  251904.0   69700.9   78612.0 74904.0 10300.0 9577.3     17    0.643   3      1.166    1.809
28160.0 10240.0  0.0   9808.1 597504.0 430347.2  251904.0   69700.9   78612.0 74904.0 10300.0 9577.3     17    0.643   3      1.166    1.809
28160.0 10240.0  0.0   9808.1 597504.0 430347.2  251904.0   69700.9   78612.0 74904.0 10300.0 9577.3     17    0.643   3      1.166    1.809
28160.0 10240.0  0.0   9808.1 597504.0 430347.2  251904.0   69700.9   78612.0 74904.0 10300.0 9577.3     17    0.643   3      1.166    1.809

查看是否有死锁

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# jstack 58256

查看堆内存数据

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# jmap -heap 58256
Attaching to process ID 58256, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.212-b10

using thread-local object allocation.
Parallel GC with 8 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 0
   MaxHeapFreeRatio         = 100
   MaxHeapSize              = 4200595456 (4006.0MB)
   NewSize                  = 88080384 (84.0MB)
   MaxNewSize               = 1399848960 (1335.0MB)
   OldSize                  = 176160768 (168.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 589299712 (562.0MB)
   used     = 93162144 (88.84634399414062MB)
   free     = 496137568 (473.1536560058594MB)
   15.808958006074844% used
From Space:
   capacity = 10485760 (10.0MB)
   used     = 10174544 (9.703201293945312MB)
   free     = 311216 (0.2967987060546875MB)
   97.03201293945312% used
To Space:
   capacity = 30408704 (29.0MB)
   used     = 0 (0.0MB)
   free     = 30408704 (29.0MB)
   0.0% used
PS Old Generation
   capacity = 257949696 (246.0MB)
   used     = 71381888 (68.0750732421875MB)
   free     = 186567808 (177.9249267578125MB)
   27.672794000889226% used

29817 interned Strings occupying 3078576 bytes.