Java OutOfMemory示例

Posted 2021-02-23

This java code, when executed, throws OOM error.

Java Console:
...
Exception in thread "main" java.lang.OutOfMemoryError
...

Heapdump Data:
...
1STHEAPFREE Bytes of Heap Space Free: 0
1STHEAPALLOC Bytes of Heap Space Allocated: 66666600
...

import java.util.ArrayList;
import java.util.List;
 
public class JavaOOM {
 
	public static void main(String[] args) {
		System.out.println("Initial freeMemory: "+Runtime.getRuntime().freeMemory()/(1024*1024));
		oom1();
 
	}
 
	private static void oom1() {
		List<String> myList = new ArrayList<String>();
		for (long i=0; ; i++) {
			myList.add(new String(i+" - "+System.currentTimeMillis()));
			if (i%100000==0) {
				System.gc();
				System.out.println("i: "+i+", freeMemory: "+Runtime.getRuntime().freeMemory()/(1024*1024));
			}
		}
	}
 
}