goroutine | 易学教程

Example for sync.WaitGroup correct?

阅读更多关于 Example for sync.WaitGroup correct?

问题 Is this example usage of sync.WaitGroup correct? It gives the expected result, but I am unsure about the wg.Add(4) and the position of wg.Done() . Does it make sense to add the four goroutines at once with wg.Add() ? http://play.golang.org/p/ecvYHiie0P package main import ( \"fmt\" \"sync\" \"time\" ) func dosomething(millisecs time.Duration, wg *sync.WaitGroup) { duration := millisecs * time.Millisecond time.Sleep(duration) fmt.Println(\"Function in background, duration:\", duration) wg.Done

How to collect values from N goroutines executed in a specific order?

阅读更多关于 How to collect values from N goroutines executed in a specific order?

问题 Below is a struct of type Stuff. It has three ints. A Number , its Double and its Power . Let\'s pretend that calculating the double and power of a given list of ints is an expensive computation. type Stuff struct { Number int Double int Power int } func main() { nums := []int{2, 3, 4} // given numbers stuff := []Stuff{} // struct of stuff with transformed ints double := make(chan int) power := make(chan int) for _, i := range nums { go doubleNumber(i, double) go powerNumber(i, power) } //

Is it safe to read a function pointer concurrently without a lock?

阅读更多关于 Is it safe to read a function pointer concurrently without a lock?

问题 Suppose I have this: go func() { for range time.Tick(1 * time.Millisecond) { a, b = b, a } }() And elsewhere: i := a // <-- Is this safe? For this question, it\'s unimportant what the value of i is with respect to the original a or b . The only question is whether reading a is safe. That is, is it possible for a to be nil , partially assigned, invalid, undefined, ... anything other than a valid value? I\'ve tried to make it fail but so far it always succeeds (on my Mac). I haven\'t been able

cancel a blocking operation in Go

阅读更多关于 cancel a blocking operation in Go

问题 I have a blocking operation in a 3rd party library that I don\'t control. It could potentially go forever. So I want to set a timeout on it. The obvious way is to wrap it with a channel and a goroutine and then select on the result with time.After . However, the problem is the goroutine running the blocking operation could potentially go forever. Here is an example to illustrate this http://repl.it/90o Is there a way to cancel a goroutine or have it garbage collected? 回答1: You can't stop a

How to stop a goroutine

阅读更多关于 How to stop a goroutine

问题 I have a goroutine that calls a method, and passes returned value on a channel: ch := make(chan int, 100) go func(){ for { ch <- do_stuff() } }() How do I stop such a goroutine? 回答1: EDIT: I wrote this answer up in haste, before realizing that your question is about sending values to a chan inside a goroutine. The approach below can be used either with an additional chan as suggested above, or using the fact that the chan you have already is bi-directional, you can use just the one... If your

Is this an idiomatic worker thread pool in Go?

阅读更多关于 Is this an idiomatic worker thread pool in Go?

I'm attempting to write a simple worker pool with goroutines. Is the code I wrote idiomatic? If not, then what should change? I want to be able to set the maximum number of worker threads to 5 and block until a worker becomes available if all 5 are busy. How would I extend this to only have a pool of 5 workers max? Do I spawn the static 5 goroutines, and give each the work_channel ? code: package main import ( "fmt" "math/rand" "sync" "time" ) func worker(id string, work string, o chan string, wg *sync.WaitGroup) { defer wg.Done() sleepMs := rand.Intn(1000) fmt.Printf("worker '%s' received: '

Is this an idiomatic worker thread pool in Go?

阅读更多关于 Is this an idiomatic worker thread pool in Go?

问题 I\'m attempting to write a simple worker pool with goroutines. Is the code I wrote idiomatic? If not, then what should change? I want to be able to set the maximum number of worker threads to 5 and block until a worker becomes available if all 5 are busy. How would I extend this to only have a pool of 5 workers max? Do I spawn the static 5 goroutines, and give each the work_channel ? code: package main import ( \"fmt\" \"math/rand\" \"sync\" \"time\" ) func worker(id string, work string, o