> > I think the second example alternative given (playground link above) has a > data race?
I’m not surprised that the race detector sees something (a read can happen during a write of the checked bool) but I don’t think this could actually cause problems because the var’s memory value will always be 0 or 1. There may be implementation details or future implementation details that cause a problem though, so one option could be to protect the bool as a shared resource with a mutex or equivalent, but I think rog’s solution is better anyway (the first one). They all involve either repeatedly checking on a timer or checking the > value of another field (like polling) to see whether the long running task > should be stopped. Right, now every iteration of the loop has more work added. Using os.Cmd may be an option, where you can call Kill on the separate process. Matt On Saturday, March 17, 2018 at 8:01:33 AM UTC-5, thepud...@gmail.com wrote: > > *> "Here's another way: https://play.golang.org/p/gEDef3LolAZ >> <https://play.golang.org/p/gEDef3LolAZ> "* > > > Hi all, > > I think the second example alternative given (playground link above) has a > data race? > > Sample race detector run just now. (The two reports are inverses of each > other: read then write vs. write then read). > > ----------------------------------------------------------------------- > go run -race stop_flag_from_gonuts.go > > . . . . . quit sending ... > after quit sent================== > . > WARNING: DATA RACE > Write at 0x00c042072000 by goroutine 8: > main.f.func1() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:13 +0x59 > > Previous read at 0x00c042072000 by goroutine 6: > main.f() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:17 +0x102 > > Goroutine 8 (running) created at: > main.f() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:11 +0x8a > > Goroutine 6 (running) created at: > main.main() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:28 +0x70 > ================== > ================== > WARNING: DATA RACE > Read at 0x00c042072000 by goroutine 6: > main.f() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:17 +0x102 > > Previous write at 0x00c042072000 by goroutine 8: > main.f.func1() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:13 +0x59 > > Goroutine 6 (running) created at: > main.main() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:28 +0x70 > > Goroutine 8 (finished) created at: > main.f() > C:/cygwin64/bin/gonuts/stop_flag_from_gonuts.go:11 +0x8a > ================== > quit called > Found 2 data race(s) > exit status 66 > ----------------------------------------------------------------------- > > --thepudds > > On Friday, March 16, 2018 at 11:04:38 AM UTC-4, matthe...@gmail.com wrote: >> >> While this is running, your select won't be receiving on the quit >>> channel, even if it is non-nil. >>> If you want to be able to cancel it, you'll need to make the code in >>> the loop responsive to the quit channel >>> (for example, by using a select like you're using in f already). >> >> >> The default select case does it: https://play.golang.org/p/jlfaXu6TZ8L >> >> Here's another way: https://play.golang.org/p/gEDef3LolAZ >> >> Matt >> >> On Friday, March 16, 2018 at 9:45:00 AM UTC-5, Sathish VJ wrote: >>> >>> All the examples I've seen use some kind of ticker to run various cases >>> of a select statement. But how does one run a long running task that is >>> still cancelable? >>> >>> >>> In the example below the quit part is never reached. >>> >>> https://play.golang.org/p/PLGwrUvKaqn (it does not run properly on >>> play.golang.org). >>> >>> package main >>> >>> >>> import ( >>> "fmt" >>> "os" >>> "time" >>> ) >>> >>> >>> func f(quit chan bool) { >>> for { >>> select { >>> case <-time.After(0 * time.Second): >>> // start long running task immediately. >>> for { >>> time.Sleep(500 * time.Millisecond) >>> fmt.Printf(". ") >>> } >>> case <-quit: >>> fmt.Println("quit called") >>> //deallocate resources in other long running task and then return >>> from function. >>> os.Exit(0) // or return >>> } >>> } >>> } >>> >>> >>> func main() { >>> var quit chan bool >>> go f(quit) >>> >>> >>> println("quit sending ... ") >>> quit <- true >>> println("after quit sent") >>> >>> >>> var i chan int >>> <-i >>> } >>> >>> >>> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
