If 100,000 concurrent clients connect to the GameServer via WebSocket, what problems might arise? How to scale such a system?

When 100,000 clients connect simultaneously to the GameServer via WebSocket, the following issues may arise:

• Resource limitations: memory, CPU, network sockets, file descriptors.
• Scalability problems: a single server cannot handle such a number of connections.
• State management: storing player states and synchronization.
• Latency and bandwidth: high load can lead to delays.

How to scale:

1. Use horizontal scaling: run multiple server instances, distribute clients through a load balancer.
2. Sharding: divide clients across servers based on certain criteria (e.g., region, ID).
3. Use efficient non-blocking I/O: in Go, this is goroutines and epoll/kqueue.
4. Optimize the protocol: minimize the amount of data transmitted.
5. Use message brokers: for synchronizing state between servers (e.g., Redis, Kafka).
6. Monitoring and auto-scaling: to respond to load growth.

Example architecture:

[Clients] -> [Load balancer] -> [GameServer clusters] -> [Shared state storage]

This approach will support high load and ensure fault tolerance.