implementing context cancellation and goroutine leaks in Go 1.20 while handling long-running requests
I'm maintaining legacy code that After trying multiple solutions online, I still can't figure this out... I'm getting frustrated with This might be a silly question, but I've been struggling with this for a few days now and could really use some help..... I'm working with a question with goroutine leaks when using context cancellation in my Go web server built with the Gorilla Mux router. My application handles long-running requests to an external API, and I want to ensure that if a client disconnects, the corresponding goroutine should also stop processing. However, I am seeing that the goroutines are still running even after the context is cancelled, leading to resource leaks. Here's a simplified version of what I have: ```go package main import ( "context" "fmt" "net/http" "time" "github.com/gorilla/mux" ) func longRunningTask(ctx context.Context) { select { case <-time.After(10 * time.Second): // Simulating a long task fmt.Println("Task completed") case <-ctx.Done(): fmt.Println("Task cancelled") } } func handler(w http.ResponseWriter, r *http.Request) { ctx, cancel := context.WithCancel(r.Context()) defer cancel() go longRunningTask(ctx) // Simulate a client disconnect after 2 seconds time.Sleep(2 * time.Second) fmt.Fprintln(w, "Response sent to client") } func main() { r := mux.NewRouter() r.HandleFunc("/longtask", handler) http.ListenAndServe(":8080", r) } ``` In this setup, I expect the `longRunningTask` to receive the cancellation signal when the client disconnects or the request completes, but instead, it continues to run until the timer finishes its sleep. I tried using `ctx.Done()` to check for cancellation, but it doesn't seem to trigger as expected. I have also checked for proper usage of `defer cancel()` in the handler, but it does not seem to help in stopping the long-running task. Is there something I'm missing? Could this be a question with the way I'm managing the context or the goroutines? Any suggestions on best practices for handling this scenario would be greatly appreciated. Has anyone else encountered this? This is part of a larger web app I'm building. This is happening in both development and production on Debian.