I've got a little network game I'm making to learn networking in Java, and I'm in need of a little insight into what my program is having issues with. My server program maxes out the heap and burns 100% of the CPU. I'm sure I've got major newbie gotchas in the code, and I'm wondering if anyone would be so kind as to point them out to me, and perhaps detail why it is such a horrible practice.
Basically, the Server class's job is to wait in socket.accept() to deal with new clients. Each client from there gets its own ConnectionThread (which deals with input) and an attached OutputStream (which handles output). I know this may be wasteful for large applications, but with the server running along with just three clients (which are set to skip rendering and only send data through the socket every ~20ms for both input and output) it cooks the CPU and the server overflows the stack.
I've got a Packet class which converts the data into a string for sending, and the receiver decodes it back into a Packet. I suspect I have some Packets laying around too long, but I don't see where. If it isn't the packets, I'm fairly certain I have SOME sort of uncontrolled exponential object growth.
Here are some snippets of relevant code. I'm happy to provide more if the problem is elsewhere.
Just for reference, here is the full code: https://github.com/taylorrobert/ProjectM2O
Server:
public Server() {
network = new NetworkManager(this);
network.setConnectionCounter(0);
entityManager = new EntityManager(this);
setListenState(true);
try {
serverSocket = new ServerSocket(PORT);
} catch (IOException e) {
System.out.println("Error in server constructor.");
System.exit(1);
}
}
public void listen() {
System.out.println("Current connectionCounter: " + network.getConnectionCounter());
while (shouldListen) {
ConnectionThread conn = null;
try {
conn = new ConnectionThread(serverSocket, this);
}
catch (Exception e) {
System.out.println("____Error constructing ConnectionThread. Could there be another instance of the server running?");
e.printStackTrace();
System.exit(1);
}
(new Thread(conn)).start();
System.out.println("Connection count: " + network.getConnectionCounter());
}
}
ConnectionThread:
public ConnectionThread(ServerSocket s, Server ser) {
resetTimer();
setActiveState(false);
server = ser;
//This UUID becomes the client's controllable player ID
//and the ID of this ConnectionThread.
connectionID = String.valueOf(UUID.randomUUID());
try {
socket = s.accept();
System.out.println("Socket ID " + connectionID + " established on: " + socket);
} catch (IOException e) {
System.out.println("Error in ConnectionThread. Is there a server already running on this port?");
}
init();
}
public void init() {
try {
out = new PrintWriter(socket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
}
catch (IOException e) {
System.out.println("Error in intializing I/O streams.");
System.exit(1);
}
//Create the output thread
OutputStream outputHandler = new OutputStream(this);
new Thread(outputHandler).start();
//Get the client up to date on all relevant data
server.getEntityManager().addPlayerEntity(getConnectionID());
server.getNetwork().pushClientInitState(getConnectionID(), this);
server.getNetwork().addConnection(this);
server.getNetwork().notifyClientsAboutNewPlayer(getConnectionID());
int s = server.getNetwork().getConnections().size();
server.getNetwork().sendConsoleMessage("Players online: " + s, this);
}
public void run() {
setActiveState(true);
System.out.println("Running ConnectionThread...");
while (isActive()) {
//System.out.println("Entity size: " + server.getEntityManager().getEntities().size());
String op = readInputStream();
if (op.equals("")) continue;
Packet packet = Packet.populateNewPacketFromString(op);
try {
incomingOpQueue.put(packet);
} catch (InterruptedException e) {
System.out.println("Server failed to add packet to outgoing queue!");
}
//Take all packets off the incoming queue and execute them in order
while (incomingOpQueue.size() > 0) {
Packet p = incomingOpQueue.poll();
PacketExecutor.executePacket(server, p, this);
}
}
}
public String readInputStream() {
String msg = "";
try {
msg = in.readLine();
msg = msg.replace("\n", "");
msg = msg.trim();
} catch (IOException e) {
return "";
}
return msg;
}
OutputStream:
public void output() {
while (parentCT.isActive()) {
UnitTester.updateAllEntityLocationsToAllClients(parentCT, parentCT.server.getEntityManager().getEntities());
while (parentCT.getOutgoingOpQueue().size() > 0) {
String packet = (parentCT.getOutgoingOpQueue().poll().getString());
if (packet.equals("")) continue;
//System.out.println("Sending " + packet + " to " + parentCT.getConnectionID());
parentCT.getOutput().println(packet);
}
}
}
