线上cpu高，如何处理

基本思路：查询占用cpu高的pid，然后查询tid线程号，jstask dump出线程信息，找到tid线程号里面自己的程序

 

LINUX

1.查看cpu占用多少

top命令，第3行

在第三行有显示CPU当前的使用情况。

[root@li676-235 ~]# top -bn 1 -i -c
top - 14:19:51 up 138 days, 7:15, 1 user, load average: 0.20, 0.33, 0.39
Tasks: 115 total, 1 running, 114 sleeping, 0 stopped, 0 zombie
Cpu(s): 4.5%us, 3.8%sy, 0.0%ni, 91.0%id, 0.6%wa, 0.0%hi, 0.0%si, 0.0%st

参数：

%us：表示用户空间程序的cpu使用率（没有通过nice调度）

%sy：表示系统空间的cpu使用率，主要是内核程序。

%ni：表示用户空间且通过nice调度过的程序的cpu使用率。

%id：空闲cpu

%wa：cpu运行时在等待io的时间

%hi：cpu处理硬中断的数量

%si：cpu处理软中断的数量

%st：被虚拟机偷走的cpu

2.通过top找到pid占用cpu最高的

然后通过ps aux | grep PID，来判断是哪个进程

3.显示进程中的线程列表

ps -mp pid -o THREAD,tid,time

找到占用cpu最高的线程tid

其次将需要的线程ID转换为16进制格式：

printf "%x\n" tid

最后打印线程的堆栈信息：

jstack pid |grep tid -A 30

可以看到程序第几行导致占用cpu高

 

Windows

打开任务管理器，查看占用cpu最大的应用

这里面是PID 2188，因为是java应用，不是idea应用

我们需要找到TID

使用的是Process Explorer v16.22，https://docs.microsoft.com/zh-cn/sysinternals/downloads/process-explorer

 

找到相应的pid，对应的线程tid，比如最高的11016.这里是10进制，需要转换成十六进制2B08

 

使用jdk文件bin里面，jstask.exe

cmd输入jstask -l PID>文件的地址

"main" #1 prio=5 os_prio=0 tid=0x0000000003654000 nid=0x2b08 runnable [0x000000000341e000]
   java.lang.Thread.State: RUNNABLE
	at java.io.FileOutputStream.writeBytes(Native Method)
	at java.io.FileOutputStream.write(FileOutputStream.java:326)
	at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
	at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
	- locked <0x00000006c21c2e80> (a java.io.BufferedOutputStream)
	at java.io.PrintStream.write(PrintStream.java:482)
	- locked <0x00000006c21c2e60> (a java.io.PrintStream)
	at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
	at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
	at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
	- locked <0x00000006c21c2fa8> (a java.io.OutputStreamWriter)
	at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
	at java.io.PrintStream.write(PrintStream.java:527)
	- eliminated <0x00000006c21c2e60> (a java.io.PrintStream)
	at java.io.PrintStream.print(PrintStream.java:597)
	at java.io.PrintStream.println(PrintStream.java:736)
	- locked <0x00000006c21c2e60> (a java.io.PrintStream)
	at com.example.demo.DemoApplicationTests.contextLoads(DemoApplicationTests.java:16)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

   Locked ownable synchronizers:
	- None

看见第一行没有，2B08

找到at com.example.demo.DemoApplicationTests.contextLoads(DemoApplicationTests.java:16)

我程序中的bug