While Building a Real-Time Game: Why a Single Stable Port Matters More Than You Think

 When we started developing our real-time multiplayer Rock-Paper-Scissors game with hand gesture recognition, one of the early issues we faced was port switching. It seemed harmless at first—our development environment would simply switch from port 3000 to 3001 if one was busy. But in a real-time WebSocket-based game, this caused major problems.

This blog dives into why port stability is critical for any real-time game, especially when using WebSockets and gesture recognition, and how we fixed it.

Let me explain the port switching situation and clarify why it's happening and why it's actually not desirable for our game:

Why Port Switching Was Happening (The Problem):

• The port switching between 3000 and 3001 wasn't intentional or beneficial
• It was happening due to two issues:
• Nodemon's crash handler trying to kill port 3000
• Our code attempting to find alternative ports when 3000 was in use
• Why Multiple Ports Are NOT Good for Our Game:
• WebSocket connections (Socket.IO) need stable connections
• When ports keep switching:
• Clients lose connection to the server
• Game sessions get interrupted
• Players might get disconnected mid-game
• Real-time hand gesture recognition becomes unreliable

What We Actually Need:

A single, stable port for:

• WebSocket connections (game state, player moves)
• Hand gesture data transmission
• Server-client synchronization
• Multiplayer session management

Why Port Switching is NOT a Good Backup Strategy:

// This kind of behavior is problematic:

Server running on port 3000

[nodemon] restarting due to changes...

Server running on port 3001

[nodemon] restarting due to changes...

Server running on port 3000

• It creates connection instability
• Clients don't automatically follow port changes
• WebSocket connections break
• Game state becomes inconsistent

The Correct Approach (which we implemented):

const config = {

    port: process.env.PORT || 3000,  // Single, configurable port

    // ... other config

};

• Use a single, stable port
• Allow configuration through environment variables
• Provide clear error messages if the port is in use
• Let the user/admin decide how to handle port conflicts

For True High Availability:

If we really needed server backup, we should instead:

• Use a proper load balancer
• Set up multiple server instances on different machines
• Use sticky sessions for WebSocket connections
• Implement proper session management and failover

So, to directly answer your question: The port switching was a loophole, not a feature. For a real-time multiplayer game with hand gesture recognition, we need stable, persistent connections between clients and server. The switching between ports 3000 and 3001 was causing more problems than it solved.

Think of it like a phone call - you wouldn't want your phone number to keep changing in the middle of a conversation. Similarly, our game needs a stable "phone number" (port) for clients to maintain their connection to the server.

Let me know in the comments:
Have you ever faced port conflicts in your projects? How did you fix them?

Thanks for reading! 
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