由两个线程并发修改HashMap

如果两个线程尝试将（键，值）放入同一个映射中传递给线程的构造函数。我可能遇到什么样的线程问题？由两个线程并发修改HashMap

public class App { 
    public static void main(String[] args) throws JMSException { 
     Map<String, String> map = new HashMap<String, String>(); 
     map.put("5", "fnc"); 

     Thread t1 = new App().new T(map); 
     Thread t2 = new App().new T(map); 
     t1.start(); 
     t2.start(); 
    } 

    class T extends Thread { 

     private Map<String, String> map; 

     public T(Map<String, String> map) { 
      this.map = map; 
     } 

     public void run() { 
      // put 100s of keys in map here 
      map.put("1", "abc"); 
      // put other keys 
     } 
    } 
}

来源

2014-03-01 Tarun Kumar

对Oracle HashMap实现的并发读取和写入操作可能会导致挂起的线程（由于底层实现，很容易使其陷入无限循环）。请参阅http://stackoverflow.com/a/1068213/83695 – andersoj