定位java最耗cpu进程

矫情吗；* 2023-06-26 08:19 22阅读 0赞

### 1.定位最耗cpu进程 ###

1.通过jps命令来查找对应的java线程

如果一个服务器上java进程很少，我们一眼就可以定位出这个线程。

77 jar
    255 Jps

2.通过top命令来查找cpu使用最高的线程

如果一个服务器上有多个java服务，那么使用top命令对多个java进程进行观察，找出耗费cpu最大的进程，从下面可以看出是PID为77的进程最耗cpu

top - 14:21:59 up 36 min,  2 users,  load average: 0.11, 0.13, 0.09
    Tasks:  13 total,   1 running,  11 sleeping,   1 stopped,   0 zombie
    %Cpu(s):  0.7 us,  3.9 sy,  0.0 ni, 95.2 id,  0.0 wa,  0.0 hi,  0.2 si,  0.0 st
    KiB Mem :  2047036 total,    92068 free,   830284 used,  1124684 buff/cache
    KiB Swap:  1048572 total,  1048492 free,       80 used.  1043460 avail Mem 
    
      PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                 
       77 root      20   0 2818704 124676  16256 S  11.0  6.1   0:31.69 java                                    
       38 root      20   0  117704   9244   7820 S   4.3  0.5   0:28.41 sshd                                    
       12 root      20   0   33392   3872   2888 S   0.3  0.2   0:01.43 redis-server

### 2.定位最耗cpu线程 ###

注意下面的pid是进程id

top -H -p <pid>
    top -H -p 77

效果如下：可以看出来最耗cpu的线程是值为91的线程

top - 14:23:26 up 37 min,  2 users,  load average: 0.02, 0.10, 0.08
    Tasks:  13 total,   1 running,  11 sleeping,   1 stopped,   0 zombie
    top - 14:23:59 up 38 min,  2 users,  load average: 0.27, 0.15, 0.10
    Threads:  14 total,   1 running,  13 sleeping,   0 stopped,   0 zombie
    %Cpu(s):  0.9 us,  4.5 sy,  0.0 ni, 94.6 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
    KiB Mem :  2047036 total,    91232 free,   831100 used,  1124704 buff/cache
    KiB Swap:  1048572 total,  1048492 free,       80 used.  1042692 avail Mem 
    
      PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND                                  
       91 root      20   0 2818704 125124  16256 R 11.3  6.1   0:30.25 java                                     
       77 root      20   0 2818704 125124  16256 S  0.0  6.1   0:00.00 java                                     
       78 root      20   0 2818704 125124  16256 S  0.0  6.1   0:02.49 java                                     
       79 root      20   0 2818704 125124  16256 S  0.0  6.1   0:00.04 java

使用 printf 函数打印出线程的16进制值（jvm里面使用的16进制来记录线程的线程号的）

printf %x 91

结果：

### 3.通过jstack来定位这个线程 ###

其中jstack是后面紧跟的值是进程的id，而后面grep命令后面紧跟的是我们线程的id

jstack <pid> | grep -C10 <tid>
    jstack 77 | grep -C10 5b

结果如下：我们可以看到就是 32 行得到代码那边是最耗cpu的，我们就找到了这个耗cpu的代码具体位置了

"Attach Listener" #15 daemon prio=9 os_prio=0 tid=0x00007ffaec001000 nid=0x9f waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
    "DestroyJavaVM" #14 prio=5 os_prio=0 tid=0x00007ffb1c008800 nid=0x4e waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
    "t1" #12 prio=5 os_prio=0 tid=0x00007ffb1cd8b800 nid=0x5b waiting on condition [0x00007ffb09dbb000]
       java.lang.Thread.State: TIMED_WAITING (sleeping)
            at java.lang.Thread.sleep(Native Method)
            at com.dada.test.arthastest.ArthasTestApplication$1.run(ArthasTestApplication.java:32)
            at java.lang.Thread.run(Thread.java:745)
    
    "Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007ffb1c140000 nid=0x57 runnable [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
    "C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007ffb1c13d000 nid=0x56 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE