Question

I am developing a Net game, in general:

I have a server which launch a serverThread for each client that has connected to it.
Its purpose is to listen to messages from the specific client and to process it on the server.
Also for each client that is opened it launch a clientThread which is a listening thread to messages from the server.
The two threads are quite simple and similar threads which implements the Runnable Interface and therefore override the run method.
Each Run method is some kind of infinite loop that has on its start the command (blocking command):

int command = m_In.readInt();

and then do a process by switch cases structure over the received command.
after process was done, the loop cause the code to return to the blocking m_In.readInt()
To wait for another command to come.

My question is: My Net game has enough options which are using the communication over this m_In, so what happens if there are two messages or more coming almost together to the clientThread, how would the dataInputStream will act?
Will it begin to process first message and after its done will grab the second which is on some kind of a queue? or it could drop the second message and it will be lost?
Maybe that stream has buffer so it stores the second message in a queue or something?

Thanks

Answer 1

Streams by their nature expect data to come in a specified order. If you have two threads writing to the same stream at the same time, bad things will happen.

Now you can certainly synchronize access to the stream and have the two thread interleave their writing (so long as you build some sort of formatting on the stream that tells the receiver how to read data), but you don’t get this by default.

Typically though, each client thread would have their own connection and thus their own stream to write into. A server can obviously read from multiple streams at the ‘same time’, and that is the normal server pattern.