在同步块内部抛出Java ConcurrentModificationException

Question

我正在开发一个接受客户端的非常基本的服务器，并将数据从一个客户端写入连接的所有其他客户端。现在它工作正常，直到其中一个客户端断开连接，此时服务器下次尝试迭代客户端列表时，我从handle方法中得到了一个concurentmodification异常。我理解synchronized（clients）关键字的方式是，一旦一个线程调用了handle并开始迭代客户端列表，那么试图在该列表上调用add / remove的任何线程都会阻塞，直到句柄完成。

private void addClientThread(Socket _socket)
{
    System.out.println("[DEBUG]: Adding client: "+_socket.getPort());
    serverThread temp = new serverThread(this,_socket);

    try
    {
        System.out.println("Server accepted new client: " + _socket+".  Spawning new handler thread");
        temp.open();
        synchronized(clients)
        {
            clients.add(temp);
        }
        temp.start();
    }
    catch(IOException ioe)
    {
        System.out.println("Error opening thread: " + ioe);
    }
}

public void remove(serverThread threadToRemove)
{
    synchronized(clients)
    {
        clients.remove(threadToRemove);
    }
    try
    {
        threadToRemove.close();
        System.out.println("Server closed client handler thread: "+threadToRemove.getId());
    }
    catch(IOException ex)
    {
        System.out.println("IO Exception while closing thread: "+ex);
    }
}

public void handle(serverThread self,byte input)
{
    synchronized(clients)
    {
        // Pass anything the client wrote to all of the other clients
        for(serverThread temp : clients)
        {
            if(!temp.equals(self))
                temp.send(input);
        }
    }
}