jstack查看某个进程堆栈信息

jstack主要用来查看某个进程内线程的堆栈信息

一个死锁的模拟代码

package test;import java.util.concurrent.Executor;import java.util.concurrent.Executors;/*** @className: test* @description: TODO 类描述* @author: mac* @date: /12/3**/public class test {public static Executor executor=Executors.newFixedThreadPool(5);public static Object lock=new Object();public static void main(String[] args) {Task task1=new Task();Task task2=new Task();executor.execute(task1);executor.execute(task2);}static class Task implements Runnable{@Overridepublic void run() {synchronized (lock){calc();}}private void calc() {int n=0;for(;;){n++;}}}}

top 查看系统中最耗资源的java进程pid

> top3913 root20 0 6751200 18888 10452 S 100.3 0.1 0:20.71 java 3494 root20 0 750324 46036 16564 S 0.7 0.3 48:31.49 containerd 4773 root20 0 577428 33312 10540 S 0.7 0.2 77:03.92 jdog-kunlunmirr23139 prometh+ 20 0 1559032 117636 28908 S 0.7 0.7 32:40.89 prometheus 1 root20 0 191144 4132 2648 S 0.3 0.0 10:33.95 systemd

找出上一步pid内最耗cpu的线程pid

> top -Hp 3913PID USERPR NI VIRT RES SHR S %CPU %MEMTIME+ COMMAND3929 root20 0 6751200 18888 10452 R 99.7 0.1 0:59.54 java 3913 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3914 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.03 java 3915 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3916 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3917 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3918 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3919 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3920 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3922 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3923 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3924 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3925 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3926 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3927 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.00 java 3928 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.01 java 3930 root20 0 6751200 18888 10452 S 0.0 0.1 0:00.01 java

计算该线程的pid的十六进制

> printf "%x\n" 3929f59

定位代码

> jstack 3913 | grep f59 -A 50"pool-1-thread-1" #9 prio=5 os_prio=0 tid=0x00007f88bc100000 nid=0xf59 runnable [0x00007f88a8a42000]java.lang.Thread.State: RUNNABLEat test.test$Task.calc(test.java:35)at test.test$Task.run(test.java:28)- locked <0x000000076d45d8d8> (a java.lang.Object)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)at java.lang.Thread.run(Thread.java:748)"Service Thread" #8 daemon prio=9 os_prio=0 tid=0x00007f88bc0da800 nid=0xf57 runnable [0x0000000000000000]java.lang.Thread.State: RUNNABLE"C1 CompilerThread2" #7 daemon prio=9 os_prio=0 tid=0x00007f88bc0bd800 nid=0xf56 waiting on condition [0x0000000000000000]java.lang.Thread.State: RUNNABLE"C2 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007f88bc0bb800 nid=0xf55 waiting on condition [0x0000000000000000]java.lang.Thread.State: RUNNABLE"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007f88bc0b8800 nid=0xf54 waiting on condition [0x0000000000000000]java.lang.Thread.State: RUNNABLE"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007f88bc0b7000 nid=0xf53 runnable [0x0000000000000000]java.lang.Thread.State: RUNNABLE"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007f88bc086000 nid=0xf52 in Object.wait() [0x00007f88a9149000]java.lang.Thread.State: WAITING (on object monitor)at java.lang.Object.wait(Native Method)- waiting on <0x000000076d408ee0> (a java.lang.ref.ReferenceQueue$Lock)at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)- locked <0x000000076d408ee0> (a java.lang.ref.ReferenceQueue$Lock)at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007f88bc081800 nid=0xf50 in Object.wait() [0x00007f88a924a000]java.lang.Thread.State: WAITING (on object monitor)at java.lang.Object.wait(Native Method)- waiting on <0x000000076d406c00> (a java.lang.ref.Reference$Lock)at java.lang.Object.wait(Object.java:502)at java.lang.ref.Reference.tryHandlePending(Reference.java:191)- locked <0x000000076d406c00> (a java.lang.ref.Reference$Lock)at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)"VM Thread" os_prio=0 tid=0x00007f88bc077800 nid=0xf4f runnable "GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007f88bc01e800 nid=0xf4b runnable "GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007f88bc020800 nid=0xf4c runnable "GC task thread#2 (ParallelGC)" os_prio=0 tid=0x00007f88bc022000 nid=0xf4d runnable "GC task thread#3 (ParallelGC)" os_prio=0 tid=0x00007f88bc024000 nid=0xf4e runnable

在dump文件中,线程一般会存在下面几种状态

RUNNABLE 线程处于执行中BLOCKED 线程被阻塞WAITING 线程正在等待