An infinite loop without a time.Sleep will block timers in other goroutines

[gopherbot]

by arclnx:

If possible, include a link to a program on play.golang.org.
1. Create a goroutine with a timer inside a for loop
2. Create an infinite loop with for {}

What is the expected output?
The timer in the goroutine should unlock itself after the duration has passed

What do you see instead?
The timer locks forever

Which compiler are you using (5g, 6g, 8g, gccgo)?
$ go version
go version go1.1.2 linux/386

Which operating system are you using?
Linux x86_64 (Ubuntu 13.10)


I am attaching a testcase

Which version are you using?  (run 'go version')


Please provide any additional information below.

Attachments:

1. test.go (227 bytes)

[davecheney]

Comment 1:

This is working as intended. 
time.Sleep is defined as it will fire _after_ the duration passed to the function, so
technically this is not a bug.
Spinning inside goroutines is a known issue and you are advised not to do it.
It is trivial to demonstrate this effect in trivial programs, but is rarely an issue in
real life

Status changed to WorkingAsIntended.

[gopherbot]

Comment 2 by arclnx:

Shouldn't the compiler then advice the user not to spin? How is anyone supposed to know
that it is advised not to do it?
Some docs point out that for {} is the equivalent of for (;;) {} and in C one doesn't
expect any side effects of that.

[dvyukov]

Comment 3:

FWIW C code with for(;;) can work the same way. There are no guarantees that there will
be some form of preemption or something.

[ianlancetaylor]

Comment 4:

Simple rule: never spin (unless you are writing embedded code using hardware interrupts).
I don't think the compiler needs to provide any advice on this.  It should just be
standard programming practice.  The Go language protects you from some things but it's
still a system programming language; it can't protect you from everything.
The way to block forever in Go is to write "select {}".