Is there a tool to detect when I forget to close goroutines?

Question

When I do this

done := make(chan bool)
for i := 0; i < 10; i++ {
    go func() {
        done <- true
    }()
}
<-done

instead of this

done := make(chan bool)
for i := 0; i < 10; i++ {
    go func() {
        done <- true
    }()
}
for i := 0; i < 10; i++ {
    <-done
}

Am I leaking goroutines if I do not close them and Is there a tool to detect when I forget to close goroutines?

Answer 1

Yes, you are leaking 9 goroutines in you first example.

I don't believe there's any tool to tell you this.

would be an interesting thing to make, if there's a way to query for all existing non-system (ie: gc) goroutines.

Probably can do something with: runtime.Stack, but it would be super-specific to a given codebase as you likely have some "good" goroutines and some "rogue" ones.

Update: Feb 4, 2016

I got curious on this, so I made a really simple (and terribly named) library to do a diff of goroutines over time. A simplistic leak detector. https://github.com/dbudworth/greak