The original article is in : http://blogs.manageengine.com/appmanager/2011/02/09/identify-java-code-consuming-high-cpu-in-linux-linking-jvm-thread-and-linux-pid/

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We can easily identify a problematic java code which leads to high CPU utilization in Linux. Let me explain the steps with the following example,

1. ?package test;
3. ?public class ThreadDumpTest {
4. ???????? public void test(){
5. ???????????????? for (int i = 0; i < 10 ; i++) {
6. ???????????????????????? Thread th=new Thread(new TR(i));
7. ???????????????????????? th.setName(“MyThread-”+(1000+i));
8. ???????????????????????? th.start();
9. ???????????????? }
10. ???????? }
11. ???????? public static void main(String[] args) {
12. ???????????????? ThreadDumpTest t=new ThreadDumpTest();
13. ???????????????? t.test();
14. ???????? }
15. ???????? private class TR implements Runnable{
16. ???????????????? int ins=0;
17. ???????????????? TR(int i){
18. ???????????????????????? ins=i;
19. ???????????????? }
20. ???????????????? public void run(){
21. ???????????????????????? while (true) {
22. ???????????????????????????????? if(ins!=5) {
23. ???????????????????????????????????????? try {
24. ???????????????????????????????????????????????? Thread.sleep(10000);
25. ???????????????????????????????????????? } catch (Exception e) {
26. ???????????????????????????????????????????????? e.printStackTrace();
27. ???????????????????????????????????????? }
28. ???????????????????????????????? }
29. ???????????????????????? }
30. ???????????????? }
31. ???????? }
32. ?}

In the above example, all the threads are in while loop. Except ‘MyThread-1005 ‘ thread, all other threads will sleep 10 secs inside the loop. The ‘MyThread-1005 ‘ thread will not enter sleep part, so it will run in while loop without sleep. Due to while loop, the ‘MyThread-1005 ‘ thread will leads to high CPU utilization.

How to identify ?

Step 1 :

Step 2 :

Step 3:

Step 4:

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