Why architecture matters here
Channel architecture matters because channels are the boundary between goroutines. Misuse causes deadlocks, races, or leaks. Right use gives you elegant concurrent code without shared mutable state.
Cost is small — channel operations are microseconds. Buffered channels use memory proportional to capacity.
Reliability depends on close discipline. Sending to closed panics; receiving from closed returns zero + closed signal.
The architecture: every element explained
Walk the diagram top to bottom.
Producer(s). One or many senders.
Channel. Typed FIFO. In Go: ch := make(chan int).
Consumer(s). One or many receivers.
Buffered vs Unbuffered. Unbuffered: send blocks until receive (rendezvous). Buffered: send until buffer full.
Close semantics. Owner closes when done. Receivers detect via idiom `v, ok := <-ch` or range loop end.
Select / poll. Multiplex over channels. Wait on multiple; wake when any ready.
Backpressure. Full buffer or unbuffered means producer waits — natural flow control.
Deadlock risk. Circular waits (A waits on B, B on A). Static analysis catches some.
Modern impls. Go (native), Rust (crossbeam, tokio mpsc), Kotlin coroutines Channel, Java Loom (in progress).
Alternatives. Actors, futures, reactive streams.
End-to-end channel flow
Trace a pipeline. Producer goroutine generates work items; sends to channel of capacity 10.
Consumer goroutine loops: for item := range ch { process(item) }.
Producer sends. Buffer fills to 10. Producer's 11th send blocks (backpressure).
Consumer processes one; buffer 9; producer's blocked send completes.
Producer finishes; closes channel. Consumer's range loop naturally ends when channel drained.
Select scenario: consumer wants to also receive shutdown signal. select { case item, ok := <-ch: if !ok return; process case <-done: return }
Fan-out: many workers on same channel; Go runtime distributes. Fan-in: many producers to one channel.
Deadlock example: two goroutines each waiting for the other's send. Runtime detects at all-goroutines-blocked in Go.