Deadlock in `signalReceivers.Stop`

[ogaca-dd]

Describe the bug There is a deadlock in signalReceivers.Stop:

• syscall.SIGINT is sent to the process
• Shutdowner.Shutdown() is called to stop the application
• signalReceivers.Stop is called and takes the lock m
• signalReceivers.Stop sends a shutdown request (recv.shutdown <- struct{}{}) and blocks on the select
• In signalReceivers.relayer, the branch case signal := <-recv.signals: is executed before case <-recv.shutdown
• The branch case signal := <-recv.signals: calls signalReceivers.Broadcast
• signalReceivers.Broadcast takes the same lock m as signalReceivers.Stop

There is a deadlock.

To Reproduce Run the following code:

func main() {
	fx.New(fx.Invoke(func(shutdowner fx.Shutdowner) {
		go func() {
			_ = syscall.Kill(syscall.Getpid(), syscall.SIGINT)
			_ = shutdowner.Shutdown()
		}()
	})).Run()
}

Expected behavior No deadlock