ConcurrentModificationException ObjectOutputStream.writeObject（）

Question

在套接字编程中，我试图将一个对象发送到服务器，然后抛出ConcurrentModificationException。它不会在每次迭代中抛出异常。 我正在尝试在服务器上发送Serializable对象。

客户端代码 -

Message request = new Message();
        request.setMessage("request");
        request.setSourceNode(node);
        System.out.println("cs enter "+ node.getId());
        for(Integer i : clientThread.keySet())
        {
            //clientThread.get(i).sendMessage("request");
            clientThread.get(i).sendMessage(request);
        }

服务器上的代码 -

public synchronized void sendMessage(Message send)
     {
         //System.out.println("Client request time stamp" + main.node.getRequestTimestamp());
         send.setDestinationNode(destinationNode);
         //System.out.println(send.getMessage() + " " + send.getSourceNode().getId() + " "+ send.getDestinationNode().getId());
         try {
            oos.writeObject(send);
            oos.reset();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
     }

StackTrace：

Exception in thread "main" java.util.ConcurrentModificationException
    at java.util.ArrayList.writeObject(ArrayList.java:766)
    at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at Client.sendMessage(Client.java:45)
    at Main.csEnter(Main.java:176)
    at Main.main(Main.java:75)