implementing Go's `sync.Mutex` in Concurrent HTTP Handlers - Race Conditions Detected
I've searched everywhere and can't find a clear answer. I just started working with I'm experiencing unexpected behavior in my Go application when using `sync.Mutex` to protect access to shared data across multiple HTTP handlers. Despite properly locking and unlocking the mutex, I am still seeing race conditions reported by the Go race detector when making concurrent requests. Here’s a simplified version of my code: ```go package main import ( "fmt" "net/http" "sync" ) var ( counter int mu sync.Mutex ) func incrementCounter(w http.ResponseWriter, r *http.Request) { mu.Lock() defer mu.Unlock() counter++ fmt.Fprintf(w, "Counter: %d", counter) } func main() { http.HandleFunc("/increment", incrementCounter) http.ListenAndServe(":8080", nil) } ``` I run multiple concurrent requests to the `/increment` endpoint using a tool like `curl` or `ab`, but I get race condition warnings when running `go run -race main.go`. The warning indicates that the `counter` variable is being accessed concurrently without proper synchronization, even though I thought the mutex should be handling it. I’ve ensured that I lock and unlock the mutex around the critical section where the counter is incremented. I also tried moving the `mu.UnLock()` statement outside of the defer call, but that didn’t fix the question. Am I missing something in my implementation, or is there a better practice I should follow to manage shared state in concurrent HTTP handlers in Go? Any insights would be greatly appreciated! My team is using Go for this mobile app. What are your experiences with this? What's the correct way to implement this?