concurrency: add timeout, pass the url as argument into goroutine, but still have concurrent write issue

concurrency/concurrency.go

@@ -1,14 +1,17 @@
 package concurrency
 
+import "time"
+
 type WebsiteChecker func(string) bool
 
 func CheckWebsites(wc WebsiteChecker, urls []string) map[string]bool {
 	results := make(map[string]bool)
 
 	for _, url := range urls {
-		go func() {
-			results[url] = wc(url)
-		}()
+		go func(u string) {
+			results[u] = wc(u)
+		}(url)
 	}
+	time.Sleep(2 * time.Second)
 	return results
 }