goroutine

问题 I tried the Go Tour exercise #71 If it is run like go run 71_hang.go ok , it works fine. However, if you use go run 71_hang.go nogood , it will run forever. The only difference is the extra fmt.Print("") in the default in the select statement. I'm not sure, but I suspect some sort of infinite loop and race-condition? And here is my solution. Note: It's not deadlock as Go didn't throw: all goroutines are asleep - deadlock! package main import ( "fmt" "os" ) type Fetcher interface { // Fetch

问题 I have the following code which implements a worker queue: package main import ( "fmt" "net/http" "io" "time" ) var ( linkQueue chan Link scraperQueue chan chan Link ) func CycleDirectory(page int) { linkQueue <- Link{Name: "asd"} } type Link struct { Name string } func (s Scraper) Start() { fmt.Println("Started") go func() { for { s.ScraperQueue <- s.Link select { case link := <-s.Link: fmt.Println(fmt.Sprintf("%v", s.Id) + ": Received " + link.Name) case <-s.QuitChan: fmt.Println("Closed")

问题 If I correctly understand how goroutines work on top of system threads - they run from queue one by one. But does it mean that every goroutine loads\unloads it's context to CPU? If yes what's difference between system threads and goroutines? The most significant problem is time-cost of context-switching. Is it correct? What mechanism lays under detecting which data was requested by which goroutine? For example: I am sending request to DB from goroutine A and doesn't wait for response and at

问题 I return to .NET after leave for a while in the 2.0 days. Now, I see a lot of APIs/libraries to manage concurrency in .NET. I like how GoRoutines feel and wish to have something alike in .NET/F#, but I'm unsure about what will be the better foundation for it. Is important to remember that goroutines work for both IO-bound and CPU-bound scenarios. P.D: I have full control of the codebase, and last .NET versions for F#/.NET in both windows & mono 来源： https://stackoverflow.com/questions/35493139

问题 I have three concurrent go routines like below, func Routine1() { mutex1.Lock() do something mutex2.Lock() mutex3.Lock() send int to routine 2 send int to routine 3 * Print Something * mutex2.Unlock() mutex3.Unlock() receive ints do something mutex2.Lock() mutex3.Lock() send int to routine 2 send int to routine 3 Print Something mutex2.Unlock() mutex3.Unlock() do something receive ints mutex1.Unlock() wg.Done() } func Routine2() { mutex2.Lock() do something mutex1.Lock() mutex3.Lock() send

问题 I'm using this to receive SNMP traps: https://github.com/soniah/gosnmp Now, lets say I want to programmatically break out of the (taken from here): err := tl.Listen("0.0.0.0:9162") What are my best approaches to this? I'm somewhat new to Golang and didnt find a way to break out of a goroutine that I have no way of modifying ("3rd party"). Thanks, 回答1: Short answer: You can't. There's no way to kill a goroutine (short of killing the entire program) from outside the goroutine. Long answer: A

问题 I have code that updates the DOM. new-recipe! calls an API to get a new recipe string. update-recipe-state next updates this state in the screen. Finally we have a call to update-transition-buttons . (defn- add-listener-to-recipe-button! [] "Listens to go button, creates a new recipe and displays it" (create-click-event-listener! (dommy/sel1 :#button-start) #(go (new-recipe!) (<! (timeout 2000)) (update-recipe-state!) (<! (timeout 2000)) (update-transition-buttons! "onboarding")))) ;; define

问题 I have one channel and the receiver is main. I spawn multiple goroutines that each send a string over the channel. Now, this causes a deadlock because I didn't close the channel properly using the close function. The thing is, I have no idea how many goroutines will be created, so there's no way to know when to close the channel. I've tried using WaitGroup, the problem is, I've read that I can't use Add in the goroutine and that I should use wg.Add(1) in the main process/goroutine, I've tried

问题 I want to run some slow routine in another goroutine, is it safe to do it like this: func someHandler(w http.ResponseWriter, r *http.Request) { go someReallySlowFunction() // sending mail or something slow fmt.Fprintf(w,"Mail will be delivered shortly..") } func otherHandler(w http.ResponseWriter, r *http.Request) { foo := int64(0) bar := func() { // do slow things with foo } go bar() fmt.Fprintf(w,"Mail will be delivered shortly..") } Is there any gotchas by doing this? 回答1: Serving each

问题 From my understanding of Go scheduler, Go scheduling algorithm is partially preemptive: goroutine switches happen when a goroutine is calling a function or blocking on I/O. Does a goroutine switch happen when sending a message to a channel? // goroutine A ch <- message // some additional code without function calls // goroutine B message := <- ch In the code above, I want the code after ch <- message in A to be executed before switching to B, is this guaranteed? or does B get scheduled right