Concurrency lets a program progress through multiple independent tasks during overlapping time intervals. Go favors goroutines and channels over a traditional threading model, keeping concurrent work practical and relatively inexpensive to manage. section 5.1 section 5.0
A practical Go implementation typically combines these pieces:
- Start a function as a goroutine with the go keyword; the caller continues immediately while the function runs independently. section 5.1 section 5.2
- Use channels as typed pipelines for sending data or signals between goroutines; unbuffered channels block by default and provide synchronization. section 5.1 section 1.2.3
- Account for application lifetime: when main returns, the program ends and active goroutines stop, so explicit waiting or coordination is required. section 5.2
- Prefer context deadlines and timeouts for production-style cancellation instead of hand-built sleeping timers. section 5.2
Concurrent counting and output
A count function can print 0 through 4 while main prints Hello World. Calling go count() allows both functions to proceed concurrently; time.Sleep makes the demonstration's ordering visible. A channel version sends 8, 6, 7, 5, 3, 0, 9, and -1 to a receiving goroutine, which stops after the negative value.
