public class MemoryLeak {
  public static void main(String[] args) {
 //由于线程一直在运行,因此ThreadLocalMap里的Inner对象一直被Thread对象强引用
    new Thread(new Runnable() {
      @Override
      public void run() {
        while (true) {
   //每次都新建一个ClassLoader实例去加载Inner类
          CustomClassLoader classLoader = new CustomClassLoader
              ("load1", MemoryLeak.class.getClassLoader(), "com.ezlippi.MemoryLeak$Inner", "com.ezlippi.MemoryLeak$Inner$1");
          try {
            Class<?> innerClass = classLoader.loadClass("com.ezlippi.MemoryLeak$Inner");
            innerClass.newInstance();
   //帮助GC进行引用处理
            innerClass = null;
            classLoader = null;
            Thread.sleep(10);
          } catch (ClassNotFoundException | IllegalAccessException | InstantiationException | InterruptedException e) {
            e.printStackTrace();
          }
        }
      }
    }).start();
  }
 //为了更快达到堆区
  public static class Inner {
    private byte[] MB = new byte[1024 * 1024];
    static ThreadLocal<Inner> threadLocal = new ThreadLocal<Inner>() {
      @Override
      protected Inner initialValue() {
        return new Inner();
      }
    };
 //调用ThreadLocal.get()才会调用initialValue()初始化一个Inner对象
    static {
      threadLocal.get();
    }
    public Inner() {
    }
  }
 //源码省略
  private static class CustomClassLoader extends ClassLoader {}

-Xms100m -Xmx100m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -XX:+PrintHeapAtGC -XX:+PrintClassHistogram -XX:+HeapDumpOnOutOfMemoryError

java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid11824.hprof ...
Heap dump file created [100661202 bytes in 1.501 secs]
Heap
 par new generation  total 30720K, used 30389K [0x00000000f9c00000, 0x00000000fbd50000, 0x00000000fbd50000)
 eden space 27328K, 99% used [0x00000000f9c00000, 0x00000000fb6ad450, 0x00000000fb6b0000)
 from space 3392K, 90% used [0x00000000fb6b0000, 0x00000000fb9b0030, 0x00000000fba00000)
 to  space 3392K,  0% used [0x00000000fba00000, 0x00000000fba00000, 0x00000000fbd50000)
 concurrent mark-sweep generation total 68288K, used 67600K [0x00000000fbd50000, 0x0000000100000000, 0x0000000100000000)
 Metaspace    used 3770K, capacity 5134K, committed 5248K, reserved 1056768K
 class space  used 474K, capacity 578K, committed 640K, reserved 1048576K
Exception in thread "Thread-0" java.lang.OutOfMemoryError: Java heap space
 at com.ezlippi.MemoryLeak$Inner.<clinit>(MemoryLeak.java:34)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
 at java.lang.reflect.Constructor.newInstance(Unknown Source)
 at java.lang.Class.newInstance(Unknown Source)
 at com.ezlippi.MemoryLeak$1.run(MemoryLeak.java:20)
 at java.lang.Thread.run(Unknown Source)

 num   #instances     #bytes class name
----------------------------------------------
  1:     6203   855158648 [B
  2:     13527    1487984 [C
  3:      298     700560 [I
  4:     2247     228792 java.lang.Class
  5:     8232     197568 java.lang.String
  6:     3095     150024 [Ljava.lang.Object;
  7:     1649     134480 [Ljava.util.HashMap$Node;
 11:      813     65040 com.ezlippi.MemoryLeak$CustomClassLoader
 12:      820     53088 [Ljava.util.Hashtable$Entry;
 15:      817     39216 java.util.Hashtable
 16:      915     36600 java.lang.ref.SoftReference
 17:      543     34752 java.net.URL
 18:      697     33456 java.nio.HeapCharBuffer
 19:      817     32680 java.security.ProtectionDomain
 20:      785     31400 java.util.TreeMap$Entry
 21:      928     29696 java.util.Hashtable$Entry
 22:     1802     28832 java.util.HashSet
 23:      817     26144 java.security.CodeSource
 24:      814     26048 java.lang.ThreadLocal$ThreadLocalMap$Entry

private byte[] KB = new byte[1024];
-Xms100m -Xmx100m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -XX:+PrintHeapAtGC -XX:+PrintClassHistogram -XX:MetaspaceSize=2m -XX:MaxMetaspaceSize=2m

java.lang.OutOfMemoryError: Metaspace
 <<no stack trace available>>
{Heap before GC invocations=20 (full 20):
 par new generation  total 30720K, used 0K [0x00000000f9c00000, 0x00000000fbd50000, 0x00000000fbd50000)
 eden space 27328K,  0% used [0x00000000f9c00000, 0x00000000f9c00000, 0x00000000fb6b0000)
 from space 3392K,  0% used [0x00000000fb6b0000, 0x00000000fb6b0000, 0x00000000fba00000)
 to  space 3392K,  0% used [0x00000000fba00000, 0x00000000fba00000, 0x00000000fbd50000)
 concurrent mark-sweep generation total 68288K, used 432K [0x00000000fbd50000, 0x0000000100000000, 0x0000000100000000)
 Metaspace    used 1806K, capacity 1988K, committed 2048K, reserved 1056768K
 class space  used 202K, capacity 384K, committed 384K, reserved 1048576K
[Full GC (Metadata GC Threshold) [CMS
Process finished with exit code 1