linux中查找java程序 cpu占用高的代码位置。

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一：测试运行代码：

package com.wang;public class Main {public static void  main(String[] args) {System.out.print(1);new Main().run();}public void run(){int i=1;for(;;){for(;;){i++;}}}}

二：在linux中运行这段代码：然后用top就会看到cpu高的进程id 6375

PID 1USER1PRNIVIRTRESSHRS%CPU%MEMTIME+COMMAND6375user1120021509642530014880S88.72.50:22.72java

三：查看进程中的线程 ps -mp 6375 -o THREAD,tid,time

USER%CPUPRISCNTWCHAHUSERSYSTEMTIDTIMEuser186.319----637900:05:16

四：转储线程快照

（./jstack 6375 > 6375）这里的6375是线程id
可以看到三中线程消耗cpu最高的是6379 转化为16进制是18eb。然后看四

五：在四中产生的转储文件（如下）找18eb这个线程。线程的调用栈就是代码中的i++;

2016-11-01 05:49:59Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.111-b14 mixed mode):"Attach Listener" #8 daemon prio=9 os_prio=0 tid=0x00007ffa44001000 nid=0x1900 waiting on condition [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007ffa6c0ce000 nid=0x18f3 runnable [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007ffa6c0b1000 nid=0x18f2 waiting on condition [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007ffa6c0af000 nid=0x18f1 waiting on condition [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007ffa6c0ad800 nid=0x18f0 runnable [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007ffa6c07a000 nid=0x18ef in Object.wait() [0x00007ffa5c6fd000]   java.lang.Thread.State: WAITING (on object monitor)at java.lang.Object.wait(Native Method)- waiting on <0x00000000f0c08e98> (a java.lang.ref.ReferenceQueue$Lock)at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)- locked <0x00000000f0c08e98> (a java.lang.ref.ReferenceQueue$Lock)at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007ffa6c075800 nid=0x18ee in Object.wait() [0x00007ffa5c7fe000]   java.lang.Thread.State: WAITING (on object monitor)at java.lang.Object.wait(Native Method)- waiting on <0x00000000f0c06b40> (a java.lang.ref.Reference$Lock)at java.lang.Object.wait(Object.java:502)at java.lang.ref.Reference.tryHandlePending(Reference.java:191)- locked <0x00000000f0c06b40> (a java.lang.ref.Reference$Lock)at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)"main" #1 prio=5 os_prio=0 tid=0x00007ffa6c009800 nid=0x18eb runnable [0x00007ffa73870000]   java.lang.Thread.State: RUNNABLEat com.wang.Main.run(Main.java:11)at com.wang.Main.main(Main.java:6)"VM Thread" os_prio=0 tid=0x00007ffa6c06e000 nid=0x18ed runnable "VM Periodic Task Thread" os_prio=0 tid=0x00007ffa6c0d1800 nid=0x18f4 waiting on condition JNI global references: 9

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