time: stop time.Ticker when it is garbage collected

[gopherbot]

by awawfumin:

Go version:

> go version
go version go1.2.2 darwin/amd64

After reading the source code http://golang.org/src/pkg/runtime/time.goc , and later
confirmed by Ian Lance Taylor
https://groups.google.com/d/msg/golang-nuts/Chx1tCs2QGg/EbEOnm18NF0J , the current
implementation of time.Ticker would leak memory in the global structure
"timers" if the Ticker is no longer referenced.

We should preferably Stop() a Ticker when it is garbage collected, or if that is
technically not feasible at the moment, at least document in
http://golang.org/pkg/time/#Ticker much like how it is emphasized to call Close() after
reading from resp.Body http://golang.org/pkg/net/http/#Client.Get .

More info about the problem, plus several possible implementation proposals (to date
none are satisfactory) can be found in
https://groups.google.com/forum/#!topic/golang-nuts/Chx1tCs2QGg

[pmezard]

Comment 1:

FWIW, the documentation part was addressed by
https://code.google.com/p/go/source/detail?r=7e130e3f9a4f

[gopherbot]

Comment 2 by robryk:

Unfortunately, we can't stop a Ticker when it's GCed. A user can hold on to a copy of
the timer from the Ticker and allow the Ticker to be garbage collected. In that case, we
don't want to stop the Ticker. In fact, Tick does exactly that.
As far as I know, there is no way to notice when the channel itself is destroyed (I
don't mean a value of type chan, but the channel that backs it). Thus, I don't see any
way of noticing when a Ticker isn't used anymore.

[gopherbot]

Comment 3 by robryk:

s/a copy of the timer/a copy of the channel/

[gopherbot]

Comment 4 by awawfumin:

I see, there's indeed a lot of complications here. Nevertheless, I think the
documentation enhancement in https://code.google.com/p/go/source/detail?r=7e130e3f9a4f
looks good. Hopefully, it can be incorporated in http://golang.org/pkg/time/#Ticker soon.

[ianlancetaylor]

Comment 6:

That doc sentence is already there on tip.golang.org.  It will move to golang.org when
1.3 is released.

[rsc]

Comment 7:

Status changed to Unfortunate.