Unbuffered Channel Deadlock (ARCH5035)

Key go.async.channel-deadlock · Severity warning · Category async

Sending on an unbuffered channel with no concurrent receiver - or receiving with no sender in the same goroutine - blocks forever. This pattern produces a deadlock that can crash the whole program.

Incorrect

func Compute() int {
  ch := make(chan int)
  ch <- 42 // no receiver, blocks forever
  return <-ch
}

Correct

func Compute() int {
  ch := make(chan int)
  go func() {
    ch <- 42 // sent on a separate goroutine
  }()
  return <-ch
}

Fix

Move the send into a separate goroutine or make the channel buffered.