java中在linux下利用jstack检测死锁

Posted 2020-06-22 lxl

首先，编写一个死锁程序

 1 package deadlock;
 2 
 3 public class testJstack {
 4     final static Object resource_1 = new Object();
 5     final static Object resource_2 = new Object();
 6 
 7     public static void main(String[] args) {
 8         Thread t1 = new Thread("t1") {
 9             public void run() {
10                 synchronized (resource_1) {
11                     try {
12                         Thread.sleep(3000);
13                     } catch (InterruptedException e) {
14                     }
15                     System.out.println("locked resource_1");
16                     synchronized (resource_2) {
17                         System.out.println("thread t1 done.");
18                     }
19                 }
20             }
21         };
22 
23         Thread t2 = new Thread("t2") {
24             public void run() {
25                 synchronized (resource_2) {
26                     System.out.println("locked resource_2");
27                     synchronized (resource_1) {
28                         System.out.println("thread t2 done.");
29                     }
30                 }
31             }
32         };
33         t1.start();
34         t2.start();
35     }
36 }

程序运行结果是：

lock resource_2
lock resource_1

接下来在终端中输入jsp查看当前运行的java程序：

7480 testJstack
13420 Jps

获取testJstack的进程ID为7480.然后使用命令：

jstack -l 7480 >deadlock.jstack

将jstack检测结果放入文件deadlock.jstack。使用vim查看该文件：

java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
        - None

   java.lang.Thread.State: RUNNABLE


   java.lang.Thread.State: BLOCKED (on object monitor)
        at testJstack$2.run(testJstack.java:29)
        - waiting to lock <0x8c087670> (a java.lang.Object)
        - locked <0x8c087678> (a java.lang.Object)


   java.lang.Thread.State: BLOCKED (on object monitor)
        at testJstack$1.run(testJstack.java:15)

   Locked ownable synchronizers:
        - None

   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
        - None

   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
   java.lang.Thread.State: RUNNABLE
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - locked <0x8c050b30> (a java.lang.ref.ReferenceQueue$Lock)

   Locked ownable synchronizers:
        - None

        - waiting on <0x8c050a30> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:485)
        - locked <0x8c050a30> (a java.lang.ref.Reference$Lock)

   Locked ownable synchronizers:
"VM Thread" prio=10 tid=0x0807e800 nid=0x260c runnable


JNI global references: 576


Found one Java-level deadlock:
=============================
"t2":
  which is held by "t1"
"t1":
  which is held by "t2"

Java stack information for the threads listed above:
===================================================
"t2":
        at testJstack$2.run(testJstack.java:29)
        - waiting to lock <0x8c087670> (a java.lang.Object)
        - locked <0x8c087678> (a java.lang.Object)
"t1":
        at testJstack$1.run(testJstack.java:15)
        - waiting to lock <0x8c087678> (a java.lang.Object)
        - locked <0x8c087670> (a java.lang.Object)

Found 1 deadlock.