服务器cpu负载过高问题排查

小灰灰 2022-06-09 06:42 273阅读 0赞

第一步 ：执行top命令，查出当前机器线程情况

top - 09:14:36 up 146 days, 20:24,  1 user,  load average: 0.31, 0.37, 0.45
    Tasks: 338 total,   1 running, 337 sleeping,   0 stopped,   0 zombie
    Cpu(s):  0.4%us,  0.4%sy,  0.0%ni, 99.2%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
    Mem:  16331456k total, 14017124k used,  2314332k free,   316724k buffers
    Swap: 16506876k total,    36200k used, 16470676k free,  5151404k cached
    
      PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                              
     6107 root      20   0 9724m 1.3g  15m S  8.0  8.4 624:22.34 java                                                                                                  
    26678 root      20   0 9643m 498m  17m S  8.0  3.1  61:34.58 java                                                                                                  
    10168 root      20   0 12.9g 4.7g  12m S  1.7 30.0 329:11.58 java                                                                                                  
    11291 root      20   0 9654m 1.2g  15m S  0.7  7.7  35:17.04 java                                                                                                  
    28662 root      20   0 15168 1436  940 R  0.7  0.0   0:00.12 top                                                                                                   
       61 root      20   0     0    0    0 S  0.3  0.0   4:10.55 ksoftirqd/14                                                                                          
       68 root      20   0     0    0    0 S  0.3  0.0 119:58.11 events/1                                                                                              
     2987 root      20   0     0    0    0 S  0.3  0.0  31:22.27 flush-253:2                                                                                           
        1 root      20   0 19344 1204  980 S  0.0  0.0   0:03.71 init

第二步：通过jstack命令dump当前内存中线程信息  
jstack 26678

[root@172_16_1_177 logs]# jstack 26678
    2017-08-30 10:34:29
    Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.79-b02 mixed mode):
    
    "Attach Listener" daemon prio=10 tid=0x00007f96dc001000 nid=0x70d5 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
    "DubboServerHandler-172.16.1.177:28082-thread-50" daemon prio=10 tid=0x00007f967c001800 nid=0x70a1 waiting on condition [0x00007f9543040000]
       java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000ca928680> (a java.util.concurrent.SynchronousQueue$TransferStack)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
        at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:359)
        at java.util.concurrent.SynchronousQueue.take(SynchronousQueue.java:925)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
    
    "DubboServerHandler-172.16.1.177:28082-thread-49" daemon prio=10 tid=0x00007f95f820c000 nid=0x708e waiting on condition [0x00007f9543081000]
       java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000ca928680> (a java.util.concurrent.SynchronousQueue$TransferStack)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
        at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:359)
        at java.util.concurrent.SynchronousQueue.take(SynchronousQueue.java:925)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
    
    "DubboServerHandler-172.16.1.177:28082-thread-48" daemon prio=10 tid=0x00007f9674001800 nid=0x7085 waiting on condition [0x00007f95430c2000]
       java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000ca928680> (a java.util.concurrent.SynchronousQueue$TransferStack)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
        at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:359)
        at java.util.concurrent.SynchronousQueue.take(SynchronousQueue.java:925)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
    
    "DubboServerHandler-172.16.1.177:28082-thread-47" daemon prio=10 tid=0x00007f95f820a000 nid=0x7084 waiting on condition [0x00007f9543103000]
       java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000ca928680> (a java.util.concurrent.SynchronousQueue$TransferStack)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
        at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:359)
        at java.util.concurrent.SynchronousQueue.take(SynchronousQueue.java:925)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
    
    "DubboServerHandler-172.16.1.177:28082-thread-46" daemon prio=10 tid=0x00007f95f8207800 nid=0x7082 waiting on condition [0x00007f9543144000]
       java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000ca928680> (a java.util.concurrent.SynchronousQueue$TransferStack)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
        at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:359)
        at java.util.concurrent.SynchronousQueue.take(SynchronousQueue.java:925)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)

> 4.1、使用方案  
> cpu飙高，load高，响应很慢  
> 方案：  
> \* 一个请求过程中多次dump  
> \* 对比多次dump文件的runnable线程，如果执行的方法有比较大变化，说明比较正常。如果在执行同一个方法，就有一些问题了。  
> 查找占用cpu最多的线程信息  
> 方案：  
> \* 使用命令： top -H -p pid（pid为被测系统的进程号），找到导致cpu高的线程id。  
> 上述Top命令找到的线程id，对应着dump thread信息中线程的nid，只不过一个是十进制，一个是十六进制。  
> \* 在thread dump中，根据top命令查找的线程id，查找对应的线程堆栈信息。  
> cpu使用率不高但是响应很慢  
> 方案：  
> \* 进行dump，查看是否有很多thread struck在了i/o、数据库等地方，定位瓶颈原因。  
> 请求无法响应  
> 方案：  
> \* 多次dump，对比是否所有的runnable线程都一直在执行相同的方法，如果是的，恭喜你，锁住了！

参考资料：[http://blog.csdn.net/rachel\_luo/article/details/8920596][http_blog.csdn.net_rachel_luo_article_details_8920596]

[http_blog.csdn.net_rachel_luo_article_details_8920596]: http://blog.csdn.net/rachel_luo/article/details/8920596