jstack命令定位死锁

心已赠人 2023-06-16 07:45 33阅读 0赞

同样的，写一个死锁代码片段，发布到虚拟机，访问引起死锁的接口。  
排查步骤：

1.  使用top或者jps定位到项目进程pid；

[root@localhost webapps]# jps
    6944 springboot.jar
    7124 Jps

1.  **获取进程pid后直接使用命令：jstack -l 6944，打印线程dump，然后全文搜索deadlock**

Found one Java-level deadlock:
    =============================
    "Thread-8":
      waiting to lock monitor 0x00007f9814003be8 (object 0x00000000eabde030, a java.lang.String),
      which is held by "Thread-7"
    "Thread-7":
      waiting to lock monitor 0x00007f9830005458 (object 0x00000000eab2fcc8, a java.lang.String),
      which is held by "Thread-8"
    
    Java stack information for the threads listed above:
    ===================================================
    "Thread-8":
            at com.daling.util.DeadLock.lambda$deadLock$1(DeadLock.java:36)
            - waiting to lock <0x00000000eabde030> (a java.lang.String)
            - locked <0x00000000eab2fcc8> (a java.lang.String)
            at com.daling.util.DeadLock$$Lambda$514/1061093170.run(Unknown Source)
            at java.lang.Thread.run(Thread.java:745)
    "Thread-7":
            at com.daling.util.DeadLock.lambda$deadLock$0(DeadLock.java:23)
            - waiting to lock <0x00000000eab2fcc8> (a java.lang.String)
            - locked <0x00000000eabde030> (a java.lang.String)
            at com.daling.util.DeadLock$$Lambda$513/204515734.run(Unknown Source)
            at java.lang.Thread.run(Thread.java:745)
    
    Found 1 deadlock.

查看上面的dump日志，Thread-8持有0x00000000eab2fcc8锁，等待0x00000000eabde030；Thread-7持有0x00000000eabde030，等待0x00000000eab2fcc8；所以Thread-8和Thread-7发生死锁。最右一行：Found 1 deadlock.

## 线程dump 文件里，值得关注的线程状态有 ##

死锁， Deadlock（重点关注）

执行中，Runnable

等待资源， Waiting on condition（重点关注）

等待获取监视器， Waiting on monitor entry（重点关注）

暂停，Suspended

对象等待中，Object.wait() 或 TIMED\_WAITING

阻塞， Blocked（重点关注）

停止，Parked