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本文主要介绍的是一款jvm排查工具箱：jvm-tools。除了对基本jvm封装外，还提供了jmx访问以及火焰图的生成。

下载

• sjk.jar - all commands wIThout mxdump@H_512_9@
• sjk-plus.jar - all commands

实例

cpu and memory usage

java -jar sjk-0.9.jar ttop -o CPU -n 10 -p pid java -jar sjk-0.9.jar ttop -o USER -n 10 -p pid java -jar sjk-0.9.jar ttop -o Sys -n 10 -p pid java -jar sjk-0.9.jar ttop -o ALLOC -n 10 -p pid

一个命令搞定排查造成cpu高的线程

root@d3daF1eca8ca:/# java -jar sjk-0.9.jar ttop -o CPU -n 10 -p 1 Monitoring threads ...  2018-01-01T07:18:26.773+0000 PRocess summary   process cpu=6.88%   application cpu=1.37% (user=1.30% sys=0.07%)   other: cpu=5.51%   thread count: 25   GC time=0.00% (young=0.00%, old=0.00%)   heap allocation rate 390kb/s   safe point rate: 1.5 (events/s) avg. safe point pause: 0.16ms   safe point sync time: 0.01% processing time: 0.02% (wallclock time) [000068] user= 1.30% sys= 0.02% alloc=  386kb/s - RMI TCP Connection(1)-172.17.0.2 [000070] user= 0.00% sys= 0.03% alloc=  4268b/s - JMX server connection timeout 70 [000047] user= 0.00% sys= 0.01% alloc=     0b/s - NioBlockingSelector.BlockPoller-1 [000060] user= 0.00% sys= 0.01% alloc=    52b/s - http-nio-8080-AsyncTimeout [000058] user= 0.00% sys= 0.00% alloc=    23b/s - http-nio-8080-ClientPoller-0 [000014] user= 0.00% sys= 0.00% alloc=     0b/s - container-0 [000002] user= 0.00% sys= 0.00% alloc=     0b/s - Reference Handler [000003] user= 0.00% sys= 0.00% alloc=     0b/s - Finalizer [000004] user= 0.00% sys= 0.00% alloc=     0b/s - Signal Dispatcher [000013] user= 0.00% sys= 0.00% alloc=     0b/s - ContainerBackgroundProcessor[StandardEngine[Tomcat]]

histo

java -jar sjk-0.9.jar hh -n 10 --dead -p pid java -jar sjk-0.9.jar hh -n 10 --dead-young -p pid java -jar sjk-0.9.jar hh -n 10 --live -p pid

查看对象统计

root@d3daf1eca8ca:/# java -jar sjk-0.9.jar hh -n 10 --live -p 1    #      Instances          Bytes  TyPE    1:         67025        9944432  [C    2:          9382        2209656  [I    3:         18413        1620344  java.lang.reflect.Method    4:         65810        1579440  java.lang.String    5:          4140        1283520  [B    6:         35735        1143520  java.util.concurrent.ConcurrentHashMap$Node    7:          8514         946936  java.lang.Class    8:         15267         610680  java.util.LinkedHashMap$Entry    9:          9027         505512  java.util.LinkedHashMap   10:         10414         494656  [Ljava.lang.Object; @R_360_1296@        475830       28175752

gc

java -jar sjk-0.9.jar gc -p pid

查看gc日志

root@d3daf1eca8ca:/# java -jar sjk-0.9.jar gc -p 1 MBean server connected Collecting GC stats ... [GC: Copy#112 time: 4ms mem: Survivor Space: 0k+135k->135k[max:17088k] Compressed Class Space: 5190k+0k->5190k[max:1048576k] Eden Space: 18496k-18496k->0k[max:137152k] Metaspace: 41247k+0k->41247k Tenured Gen: 27515k+0k->27515k[max:342720k]] [GC: Copy#113 time: 2ms interval: 6649ms mem: Survivor Space: 135k+304k->439k[max:17088k,rate:45.83kb/s] Compressed Class Space: 5243k+0k->5243k[max:1048576k,rate:0.00kb/s] Eden Space: 18496k-18496k->0k[max:137152k,rate:-2781.77kb/s] Metaspace: 41696k+0k->41696k[rate:0.00kb/s] Tenured Gen: 27515k+0k->27515k[max:342720k,rate:0.00kb/s]] [GC: Copy#114 time: 3ms interval: 675ms mem: Survivor Space: 439k+779k->1219k[max:17088k,rate:1154.48kb/s] Compressed Class Space: 5338k+0k->5338k[max:1048576k,rate:0.00kb/s] Eden Space: 18496k-18496k->0k[max:137152k,rate:-27401.48kb/s] Metaspace: 42470k+0k->42470k[rate:0.00kb/s] Tenured Gen: 27515k+0k->27515k[max:342720k,rate:0.00kb/s]]

stack

## collect 30 seconds java -jar sjk-0.9.jar stcap -o dump.std -t 30000 -p pid java -jar sjk-0.9.jar stcap -o dump.std -p pid

dump线程堆栈

root@d3daf1eca8ca:/# java -jar sjk-0.9.jar stcap -o dump.std -p 1 Writing to /dump.std Collected 506 Collected 1012 Collected 1518 Collected 2001 Collected 2507 //...... Trace dumped: 123211

查看堆栈或生成火焰图

java -jar sjk-0.9.jar ssa -f dump.std --print java -jar sjk-0.9.jar ssa -f dump.std --histo java -jar sjk-0.9.jar ssa -f dump.std --flame > flame.svg

jmx

java -jar sjk-0.9.jar --help mx java -jar sjk-0.9.jar mx -mi -b java.lang:type=Threading -p pid java -jar sjk-0.9.jar mx -mg -b java.lang:type=Memory -f HeapMemoryUsage -p pid

查看jmx

root@d3daf1eca8ca:/# java -jar sjk-0.9.jar mx -mg -b java.lang:type=Memory -f HeapMemoryUsage -p 1 java.lang:type=Memory committed: 68194304 init:      33554432 max:       508887040 used:      49297880

小结

使用ttop命名查看cpu高的线程，以及使用stack stcap和ssa生成火焰图相当便利，值得推荐。

doc

• jvm-tools