Java program consumes CPU 100% lookup method

cause of the problem: because the HashMap is non-thread-safe, it causes a dead loop during multithreaded access.

To find the problem method:
1.

Java code

1. Top

Find the CPU-intensive process number such as: 27377

2.

Java code

1. Top-p 27377-h

Find out all the threads under this process, and then find the CPU thread number that consumes the most: 27433

3.

Java code

1. Python hex (27433)

Converts a decimal number to a 16 binary such as: 0x6b29

4.

Java code

1. Jstack 27377 >cpu.log

Print the Java stack information for this process number to a file

5.

Java code

1. grep 0x6bz8 Cpu.log

Look at the threads in the Java stack, nid:
"FoundationTaskExecutor-2" prio=10 tid=0x00007f064c041000 nid=0x6b28 runnable [0x00007f069f5da000]

6.

Java code

1. Vim Cpu.log

Find the contents of nid=0x6b28 such as:

Java code

2. "FoundationTaskExecutor-2" prio=tid=0x00007f064c041000 nid= 0x6b28runnable [0x00007f069f5da000]
4. Java.lang.Thread.State:RUNNABLE
6. At Java.util.HashMap.get (Hashmap.java:)
8. At *********************************** (Wareserviceimpl.java: +)
10. At *********************************** (Mid2foundationtask.java:127)
12. At *********************************** (Mid2foundationtask.java:)
14. At *********************************** $FoundationThreadImpl. Run (Mid2foundationtask.java:
16. At Java.util.concurrent.ThreadPoolExecutor.runWorker (Threadpoolexecutor.java:1110)
18. At Java.util.concurrent.threadpoolexecutor$worker.run (Threadpoolexecutor.java:603)
20. At Java.lang.Thread.run (Thread.java:722)

Java program consumes CPU 100% lookup method