CPU占用100%排查过程
排查过程
1、top
通过top命令找到,消耗CPU最高的PID,从下图发现PID为15913
2、top -p 15913 -H
加上-H 选项可以看到该进程的相关线程信息,从下图中可知最耗CPU的两个PID分别是15924和15925,对应的16进制为0x3E34和0x3E35
3、jstack 15913 > jstack.log
jstack命令可以得到线程堆栈信息,根据这些线程堆栈信息,可以去查看java程序出现的问题,如检测死。jstack.log的完整内容在文章最后发出来。
在日志的最后面找到0x3e34 和 0x3e35,对应的是GC线程,由此猜想可能是不停地GC导致CPU占用过高。
需要注意的是,在单核机器上,根本看不到GC线程,这个16进制数指向的是JVM Thread,试了好几次都是这样,一开始在这上面浪费太多时间了。
jstack 15913 | grep -A 10 0x3e34
4、jstat -gcutil 15193 1000 20
以上命令代码每过一秒打印一次gc情况,打印20次。
参数项说明如下:
由上图可知,20s内发生了13次Full GC,所以问题就是Full Gc 太频繁导致的,内存使用率太高,猜测可能是因为jvm分配的内存太小了。
5、jmap -heap 15193
以上命令用于查看java进程的JVM内存情况
最大内存为948M,老年代632M,使用率已经无线接近100%。机器有4G内存,但为该进程分配的JVM最大内存只有948M.
6、jmap -dump:format=b,file==heap.hprof 15193
以上命令用于导出jvm内存信息,这个我暂时也没看出什么。
- 增大堆内存
-Xms2048m -Xmx2048m ,增大堆内存到2048M,重启查看效果。
说明:系统启动之后3s内,CPU占用还是100%,接下来就降下来了。 通过jstat查看GC情况,发生了16次YGC,发生了12次 FGC,难道是系统启动的时候,创建了大量的对象?
不过接下来系统运行平稳,先观察一段时间看看。
jstack日志
2019-02-25 16:16:48
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.73-b02 mixed mode):
"Attach Listener" #133 daemon prio=9 os_prio=0 tid=0x00007f023000e000 nid=0x57b9 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
"http-nio-8080-exec-12" #132 daemon prio=5 os_prio=0 tid=0x00007f0220018800 nid=0x5419 waiting on condition [0x00007f020fefd000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c79b3f10> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:103)
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:31)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
"http-nio-8080-exec-11" #130 daemon prio=5 os_prio=0 tid=0x00007f022c62a800 nid=0x4dcd waiting on condition [0x00007f020f4d9000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c79b3f10> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:103)
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:31)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
"Curator-TreeCache-5" #53 daemon prio=5 os_prio=0 tid=0x00007f022008e800 nid=0x3eb9 waiting on condition [0x00007f020c89c000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c83319a8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"Curator-TreeCache-4" #52 daemon prio=5 os_prio=0 tid=0x00007f02108ab000 nid=0x3eac waiting on condition [0x00007f020c99d000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c99900c0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"Curator-TreeCache-3" #51 daemon prio=5 os_prio=0 tid=0x00007f0240011000 nid=0x3eab waiting on condition [0x00007f020cc9e000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c615a470> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"Curator-TreeCache-2" #49 daemon prio=5 os_prio=0 tid=0x00007f02100c0000 nid=0x3ea9 waiting on condition [0x00007f020cea0000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c7c0daa8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"Curator-TreeCache-1" #48 daemon prio=5 os_prio=0 tid=0x00007f0240001800 nid=0x3ea8 waiting on condition [0x00007f020d801000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c7fa0a68> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"Curator-TreeCache-0" #47 daemon prio=5 os_prio=0 tid=0x00007f0220085000 nid=0x3ea6 waiting on condition [0x00007f020d902000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c9991620> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"DestroyJavaVM" #46 prio=5 os_prio=0 tid=0x00007f0264008800 nid=0x3e31 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
"Curator-Framework-0" #45 daemon prio=5 os_prio=0 tid=0x00007f026560c000 nid=0x3ea0 waiting on condition [0x00007f020da03000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c63cfc68> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at java.util.concurrent.DelayQueue.take(DelayQueue.java:211)
    at java.util.concurrent.DelayQueue.take(DelayQueue.java:70)
    at org.apache.curator.framework.imps.CuratorFrameworkImpl.backgroundOperationsLoop(CuratorFrameworkImpl.java:804)
    at org.apache.curator.framework.imps.CuratorFrameworkImpl.access$300(CuratorFrameworkImpl.java:64)
    at org.apache.curator.framework.imps.CuratorFrameworkImpl$4.call(CuratorFrameworkImpl.java:267)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
"main-EventThread" #44 daemon prio=5 os_prio=0 tid=0x00007f0265485800 nid=0x3e9f waiting on condition [0x00007f020db04000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c63cf5d8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
     
                     
                    
                 
                    
                
