You have to declare your channel variable outside the loop if you want to re-use it in each iteration (errors and context omitted for brevity): package main import “fmt” func main() { var pipeline Pipeline pipeline.Steps = append(pipeline.Steps, AddBang{}, AddBang{}, AddBang{}, ) src := make(chan Message) pipe := src for _, s := range pipeline.Steps … Read more
Slices are references to arrays. When modifying a slice without copying it, the underlaying array will be modified. Therefore, all slices that point to the same underlaying array will see this change. solved Why does this goroutine behave like it’s call by reference?
Two issues: don’t copy sync.WaitGroup: from the docs: A WaitGroup must not be copied after first use. you need a wg.Add(1) before launching your work – to pair with the wg.Done() wg.Add(1) // <- add this go func (wg *sync.WaitGroup …) { // <- pointer }(&wg, quitSig) // <- pointer to avoid WaitGroup copy https://go.dev/play/p/UmeI3TdGvhg … Read more
Program execution: When the function main returns, the program exits. It does not wait for other (non-main) goroutines to complete. 1- main is goroutine too, you need to wait for other goroutines to finish, and you may use time.Sleep(5 * time.Second) for 5 Seconds wait, try it on The Go Playground: package main import ( … Read more
I haven’t analyzed all of it, but definitely the modification of mapStore from multiple goroutines is unsafe: mapStore[*res.someData] = append(mapStore[*res.someData], res) But as a starting point, run this under the race detector. It’ll find many problems for you. This is also clearly unsafe: resSlice := append(resSlice, res) But it also doesn’t quite do what you … Read more
Finally figured the answer… The problem was that I needed to close my monitoringChan in the first goroutine and then monitor (Defer wg.close()) in the second goroutine. Worked great when I did that! https://play.golang.org/p/fEaZXiWCLt- solved Goroutine loop not completing
Problem Your first version has a synchronisation bug, which manifests itself as a data race: $ go run -race main.go 0 (PrintAddr): 0xc0000b4018 0 (PrintAddr): 0xc0000c2120 ================== WARNING: DATA RACE Write at 0x00c0000b4018 by main goroutine: main.main() redacted/main.go:29 +0x1e5 Previous read at 0x00c0000b4018 by goroutine 7: main.(*User).PrintAddr() redacted/main.go:19 +0x44 Goroutine 7 (finished) created at: main.main() … Read more
I found the answer with the help of a fellow Gopher from the community. The line of code containing srv.ListenAndServe() is a blocking line of code causing the log after this line of code not to happen. In my original code I demonstrated in my earlier blog I had this log in front of the … Read more
Consider a worker pool pattern like this: https://go.dev/play/p/p6SErj3L6Yc In this example application, I’ve taken out the API call and just list the file names. That makes it work on the playground. A fixed number of worker goroutines are started. We’ll use a channel to distribute their work and we’ll close the channel to communicate the … Read more
You can’t kill a goroutine from outside – you can’t even reference a specific goroutine; nor can you abort a blocking operation. You can, however, move the for to the outside: go func() { for { select { case close := <-closeChan: return 0 case i,ok := <-c: // do stuff if !ok { // … Read more