add stuck examples

examples/stuck-deadlock/go.mod

@@ -0,0 +1,3 @@
+module github.com/felixge/go-profiler-notes/examples/stuck-program
+
+go 1.15

examples/stuck-deadlock/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"sync"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+func run() error {
+	var (
+		a = &sync.Mutex{}
+		b = &sync.Mutex{}
+	)
+	go bob(a, b)
+	go alice(a, b)
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	<-c
+	return nil
+}
+
+func bob(a, b *sync.Mutex) {
+	for {
+		fmt.Println("bob is okay")
+		a.Lock()
+		b.Lock()
+		a.Unlock()
+		b.Unlock()
+	}
+}
+
+func alice(a, b *sync.Mutex) {
+	for {
+		fmt.Println("alice is okay")
+		b.Lock()
+		a.Lock()
+		b.Unlock()
+		a.Unlock()
+	}
+}

examples/stuck-producer-worker/go.mod

@@ -0,0 +1,3 @@
+module github.com/felixge/go-profiler-notes/examples/stuck-program
+
+go 1.15

examples/stuck-producer-worker/main.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"os"
+	"os/signal"
+	"time"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	rand.Seed(time.Now().UnixNano())
+
+	workCh := make(chan int)
+	go worker(workCh)
+	go producer(workCh)
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	<-c
+	return nil
+}
+
+func producer(workCh chan<- int) {
+	for msg := 0; ; msg++ {
+		workCh <- msg
+		fmt.Printf("producer sent: %d\n", msg)
+		if rand.Int63n(10) == 0 {
+			takeNap()
+		}
+	}
+}
+
+func worker(workCh <-chan int) {
+	for {
+		msg := <-workCh
+		fmt.Printf("worker received: %d\n", msg)
+		if rand.Int63n(10) == 0 {
+			takeNap()
+		}
+	}
+}
+
+func takeNap() {
+	var forever chan struct{}
+	<-forever
+}