1. 查看占用cpu占用过高进程的pid

• 使用 top名称查看
  
• 这里可以看的出来进程是20943

2. 查看该进程中哪个线程占用大量 CPU

ps -mp 20943 -o THREAD,tid,time  | grep $(ps -mp 20943 -o THREAD,tid,time |awk 'NR>2 {print $2}'|sort -nr|head -1)|head -1
root      1.0  19    - futex_    -      - 20956 00:01:19

3. 将线程ID转换成16进制

printf "%x\n" 20956
51dc

4. 使用 jstack命令，查看线程转储信息

jstack 20943 | grep 51dc -A 10 -B 10
        at org.apache.catalina.core.StandardServer.await(StandardServer.java:453)
        at org.apache.catalina.startup.Catalina.await(Catalina.java:777)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:723)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:321)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:455)

"VM Thread" os_prio=0 tid=0x00007fba7c078800 nid=0x51dc runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007fba7c01f800 nid=0x51d4 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007fba7c021000 nid=0x51d5 runnable

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x00007fba7c023000 nid=0x51d6 runnable

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x00007fba7c024800 nid=0x51d7 runnable

"VM Periodic Task Thread" os_prio=0 tid=0x00007fba7c2a0800 nid=0x5217 waiting on condition

#假如有问题可以从这里面信息查看问题