Question

I am currently writing naive network code for a project and a mate hinted me at the possibility that when I send a package of information from the server to all clients in an iterative fashion I might get intense lag when one of the clients is not responding properly.

He is reknown for trolling so I was kind of sceptical when implementing a secondary thread that is now responsible to send data over to a client, having a queue that the Server simply adds the packages over that is then read by the thread to send data.

The question I now have after thinking it over is weather or not the OutputStream of a Java Socket actually queues the stuff he wants to send by itself, thus eliminating the need of a queue beforehand. The possibility of having intense problems occurrs only when the Server is blocking as long as he does not get a response from a client that the sent object was recieved.

Thanks.

Answer 1

Of course, when you write to a socket, this write is buffered. Socket object have a setSendBufferSize() method for setting this buffer size. If your write can be cached in this buffer, then of course, you may iterate immediately on the following socket. Otherwise this buffer need to be flushed to the client immediately. So, during flushing you are going to be blocked. If you want to avoid being blocked while flushing the buffer, you have to use a SocketChannel in non blocking I/O.
Anyway, the best option for writing to many socket concurrently, is to manage each socket with a different thread, so that all writes may be executed at the same time.