CPU over high diagnosis and troubleshooting

1： Code preparation

Loop printing random numbers

public class TestCPUHigh {
    

    public static void main(String[] args) {
    

        while (true){
    
            System.out.println(new java.util.Random().nextInt(66669999));
        }
    }
}

2： The phenomenon

pid = 5783 The process of is very expensive

3： The diagnosis

3.1：top

3.2： Locate the process jps

3.3： Go to code

Specific threads pid 5783

ps -mp 5783-o THREAD,tid,time

3.4： Hexadecimal conversion

Threads id Switch to 16 Base number ( Letter lowercase , If there are letters ) The thread in the figure takes a long time TID=5784 convert to 16 Base number 1698

3.5：jstack location

jstack 5783 | grep 1698 -A60

View stack information 60 That's ok

3.6： Find familiar classes

Find the class from your project find TestCPUHigh.java Of the 6 That's ok , Diagnosis complete