resource leak go routine demo

concurrency/goroutine_leak/main.go

@@ -0,0 +1,49 @@
+package main
+
+import "fmt"
+
+// The goroutine has a few paths to termination:
+// • When it has completed its work.
+// • When it cannot continue its work due to an unrecoverable error.
+// • When it’s told to stop working
+
+/**
+We get the first two paths for free—these paths are your algorithm—but what about
+work cancellation? This turns out to be the most important bit because of the net‐
+work effect: if you’ve begun a goroutine, it’s most likely cooperating with several other
+goroutines in some sort of organized fashion.
+**/
+
+func main() {
+
+}
+
+// Here we see that the main goroutine passes a nil channel into doWork. Therefore, the
+// strings channel will never actually gets any strings written onto it, and the goroutine
+// containing doWork will remain in memory for the lifetime of this process (we would
+// even deadlock if we joined the goroutine within doWork and the main goroutine).
+// In this example, the lifetime of the process is very short, but in a real program, gorou‐
+// tines could easily be started at the beginning of a long-lived program. In the worst
+// case, the main goroutine could continue to spin up goroutines throughout its life,
+// causing creep in memory utilization.
+func resourceLeak() {
+	doWork := func(strings <-chan string) <-chan interface{} {
+		completed := make(chan interface{})
+		go func() {
+			defer fmt.Println("doWork exited.")
+			defer close(completed)
+			for s := range strings {
+				// Do something interesting
+				fmt.Println(s)
+			}
+		}()
+		return completed
+	}
+	doWork(nil)
+	// Perhaps more work is done here
+	fmt.Println("Done.")
+}
+
+func cancellationSignal() {
+
+}

for-range-semantics/main.go

@@ -0,0 +1,21 @@
+package main
+
+import "fmt"
+
+type user struct {
+	name  string
+	email string
+}
+
+func main() {
+	users := []user{
+		{"Bill", "bill@email.com"},
+		{"Lisa", "lisa@email.com"},
+		{"Nancy", "nancy@email.com"},
+		{"Paul", "paul@email.com"},
+	}
+
+	for i, u := range users {
+		fmt.Println(i, u)
+	}
+}