Java program with step by step instructions on how to generate a heap dump

generate_heap_dump.md

Generating a Heap Dump in Java

1. Create a Java program with the following contents

import java.util.ArrayList;
import java.util.List;

public class GenarateHeapDump {
  public static void main(String[] args) {
    List<byte[]> list = new ArrayList<>();
    int index = 1;
    while (true) {
      // 1MB each loop, 1 x 1024 x 1024 = 1048576
      byte[] b = new byte[1048576];
      list.add(b);
      Runtime rt = Runtime.getRuntime();
      System.out.printf("[%d] free memory: %s%n", index++, rt.freeMemory());
    }
  }
}

2. Compile the program

javac GenerateHeapDump.java

3. Create a directory to store heap dump files

I prefer to do it this way to keep my files isolated and avoid confusion.

mkdir dumpFiles

3. Run the program

java -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/home/username/dumpFiles Solution

The above command will generate a heap dump file in the directory /home/username/dumpFiles which will have a name java_pid<pid>.hprof