Use jpofiler tool to analyze the cause of OOM

You can see the error in the first few lines of the code ： Memory snapshot analysis tool ,MAT,Jprofiler( recommend )
Debug, Analyze the code line by line

MAT,Jprofiler effect ：

• analysis Dump Memory files , Quickly locate memory leaks
• Get the data in the heap
• Get big objects
  …

download JProfiler plug-in unit

After installing the plug-in , Make sure you reboot ！

download Jprofiler Software

Download address ：http://www.xue51.com/soft/12717.html#xzdz
Without brains, the next step is ! It is best to customize the path ~

Plug in connection software

Start testing

1、 add to VM Options

Explanation of command code ：

-Xms1m -Xmx8m -XX:+HeapDumpOnOutOfMemoryError

• -Xms : Set the initialization memory allocation size
• -Xmx : Set the maximum allocated memory , Default
• -XX:+PrintGCDetails : Print GC Garbage collection information
• -XX:+HeapDumpOnOutOfMemoryError : OOM DUMP

2、 Test code

import java.util.ArrayList;

public class Demo {
    

    public static void main(String[] args) {
    
        ArrayList<Demo> list = new ArrayList<>();
        int count = 0;
        try {
    
            while(true){
    
                list.add(new Demo());// utilize JPofiler Tools , You can find out the problem of this line of code 
                count = count +1;
            }
        } catch (Exception e) {
    
            System.out.println("count"+count);
            e.printStackTrace();
        }

    }
}

3、 Find the generated file

4、 Analyze faults

Although I know there is something wrong with the big object , How do we know which line of code is wrong ？

So let's look down ~