chore: updated examples

Author: ziccardi

examples/routine_leak/example2/README.md

@@ -6,8 +6,8 @@ naked code of `step1` to the full integration in the last step.
 
 The application we are going to use for this demonstration is very simple:
 
-1. The `main` function starts the `doJob` go routine and then, every 4 seconds, prints the `pproof` goroutine dump
-2. `doJob` runs indefinitely and every 50 milliseconds invokes the `foo` function
-3. `foo` just invokes `bar` wich in turn starts the `parentGoRoutine` routine
-4. `parentGoRoutine` starts the `doInterestingStuff` routine passing a random number between 0 and 99
-5. `doInterestingStuff` hangs indefinitely if the received value is a multiple of 4, otherwise exits
+1. The `main` function repeatedly starts cycles where it processes multiple websites.
+   For each cycle, randomly selects 10 website URLs from a predefined list.
+   For each selected URL, asynchronously invokes the `getWebsiteResponseSize`
+2. The `getWebsiteResponseSize` asynchronously calls the `getResponseSize` and do some fun stuff with the result
+3. The `getResponseSize` contacts the site and returns the response size

examples/routine_leak/example2/data/data.go

@@ -0,0 +1,69 @@
+package data
+
+var Websites = []string{
+	"https://google.com",
+	"https://facebook.com",
+	"https://youtube.com",
+	"https://amazon.com",
+	"https://wikipedia.com",
+	"https://instagram.com",
+	"https://linkedin.com",
+	"https://reddit.com",
+	"https://ebay.com",
+	"https://microsoft.com",
+	"https://apple.com",
+	"https://walmart.com",
+	"https://espn-bad.com",
+	"https://bbc.com",
+	"https://cnn.com",
+	"https://foxnews.com",
+	"https://nytimes.com",
+	"https://forbes.com",
+	"https://cnbc.com",
+	"https://theguardian.com",
+	"https://nbcnews.com",
+	"https://abc.com",
+	"https://time.com",
+	"https://nationalgeographic.com",
+	"https://wired-bad.com",
+	"https://techcrunch.com",
+	"https://engadget.com",
+	"https://gizmodo.com",
+	"https://mashable.com",
+	"https://stackoverflow.com",
+	"https://github.com",
+	"https://medium-bad.com",
+	"https://dropbox.com",
+	"https://box.com",
+	"https://slack.com",
+	"https://zoom.com",
+	"https://stripe.com",
+	"https://airbnb.com",
+	"https://booking.com",
+	"https://hotels-bad.com",
+	"https://kayak.com",
+	"https://monster.com",
+	"https://edx.com",
+	"https://duolingo-bad.com",
+	"https://britannica-bad.com",
+	"https://dictionary.com",
+	"https://merriam-webster.com",
+	"https://thesaurus.com",
+	"https://weather-bad.com",
+	"https://trulia-bad.com",
+	"https://epicurious.com",
+	"https://tasteofhome.com",
+	"https://healthline.com",
+	"https://webmd.com",
+	"https://mayoclinic-bad.com",
+	"https://everydayhealth.com",
+	"https://livestrong.com",
+	"https://fool-bad.com",
+	"https://seekingalpha.com",
+	"https://nerdwallet.com",
+	"https://bankrate.com",
+	"https://creditkarma.com",
+	"https://mint.com",
+	"https://fidelity.com",
+	"https://vanguard.com",
+}

examples/routine_leak/example2/step1/README.md

@@ -3,22 +3,22 @@
 In this step, we will use the native `go` keyword to start go routines.
 The code is very simple:
 
-1. The `main` function starts the `doJob` go routine and then, every 4 seconds, prints the `pproof` goroutine dump
-2. `doJob` runs indefinitely and every 50 milliseconds invokes the `foo` function
-3. `foo` just invokes `bar` wich in turn starts the `parentGoRoutine` routine
-4. `parentGoRoutine` starts the `doInterestingStuff` routine passing a random number between 0 and 99
-5. `doInterestingStuff` hangs indefinitely if the received value is a multiple of 4, otherwise exits
+1. The `main` function repeatedly starts cycles where it processes multiple websites.
+   For each cycle, randomly selects 10 website URLs from a predefined list.
+   For each selected URL, asynchronously invokes the `getWebsiteResponseSize`
+2. The `getWebsiteResponseSize` asynchronously calls the `getResponseSize` and do some fun stuff with the result
+3. The `getResponseSize` contacts the site and returns the response size
 
 Running the application we can see how the total number of goroutine keeps increasing:
 ```
-goroutine profile: total 32
-20 @ 0x100e9caa8 0x100e7d520 0x100ef588c 0x100ea42b4
-#	0x100ef588b	main.doInterestingStuff+0x3b
+goroutine profile: total 18
+14 @ 0x102d71768 0x102d361a8 0x102d70a10 0x102db7a38 0x102db830c 0x102db82fd 0x102e451d8 0x102e4d974 0x102e87430 0x102dcd820 0x102e87610 0x102e84dac 0x102e8ad44 0x102e8ad45 0x102eb83b4 0x102d9d940 0x102ee5b18 0x102ee5aed 0x102ee6148 0x102ef6b50 0x102ef60c8 0x102d79aa4
+#	0x102d70a0f	internal/poll.runtime_pollWait+0x9f	
 ...
 ...
-goroutine profile: total 50
-38 @ 0x100e9caa8 0x100e7d520 0x100ef588c 0x100ea42b4
-#	0x100ef588b	main.doInterestingStuff+0x3b
+goroutine profile: total 33
+26 @ 0x102d71768 0x102d361a8 0x102d70a10 0x102db7a38 0x102db830c 0x102db82fd 0x102e451d8 0x102e4d974 0x102e87430 0x102dcd820 0x102e87610 0x102e84dac 0x102e8ad44 0x102e8ad45 0x102eb83b4 0x102d9d940 0x102ee5b18 0x102ee5aed 0x102ee6148 0x102ef6b50 0x102ef60c8 0x102d79aa4
+#	0x102d70a0f	internal/poll.runtime_pollWait+0x9f
 ```
 
-We can see that the leaked routine os the `doInterestingStuff` but we have no idea of the context of execution.
+Understanding which routine we are leaking is not immediate.

examples/routine_leak/example2/step1/app_leaking_routine.go

@@ -1,44 +1,71 @@
 package main
 
 import (
+	"fmt"
+	"github.com/openshift-online/async-routine/examples/routine_leak/example2/data"
+	"io"
 	"math/rand"
+	"net/http"
 	"os"
 	"runtime/pprof"
+	"strconv"
 	"time"
 )
 
 func main() {
-	go doJob()
-
 	for {
-		time.Sleep(4 * time.Second)
+		for i := 0; i < 10; i++ {
+			url := data.Websites[rand.Intn(len(data.Websites))]
+			go doJob(url)
+			time.Sleep(500 * time.Millisecond)
+		}
 		_ = pprof.Lookup("goroutine").WriteTo(os.Stdout, 1)
 	}
-
 }
 
-func doJob() {
-	for {
-		foo()
-		time.Sleep(50 * time.Millisecond)
-	}
+func doJob(url string) {
+	resultChan := make(chan int64)
+	go getResponseSize(url, resultChan)
+	size := <-resultChan
+	// do something fun with the size - here we just avoid the compilation error
+	size = size
 }
 
-func foo() {
-	bar()
-}
+// getResponseSize fetches the given URL and sends the response size (in bytes) to the provided channel.
+// Returns an error if the site does not exist or the request fails.
+func getResponseSize(url string, ch chan<- int64) error {
+	// Perform the HTTP request
+	res, err := http.Get(url)
+	if err != nil {
+		return fmt.Errorf("site unreachable: %w", err)
+	}
+	defer res.Body.Close()
 
-func bar() {
-	go parentGoroutine()
-}
+	// Handle HTTP errors
+	if res.StatusCode != http.StatusOK {
+		switch res.StatusCode {
+		case http.StatusNotFound:
+			return fmt.Errorf("site does not exist (404 Not Found)")
+		default:
+			return fmt.Errorf("invalid HTTP response: %d %s", res.StatusCode, http.StatusText(res.StatusCode))
+		}
+	}
 
-func parentGoroutine() {
-	go doInterestingStuff(rand.Intn(100))
-	time.Sleep(500 * time.Millisecond)
-}
+	// Try to use Content-Length header if available
+	if contentLength := res.Header.Get("Content-Length"); contentLength != "" {
+		size, err := strconv.ParseInt(contentLength, 10, 64)
+		if err == nil && size > 0 {
+			ch <- size
+			return nil
+		}
+	}
 
-func doInterestingStuff(value int) {
-	if value%4 == 0 {
-		select {}
+	// Calculate the size by reading the response body
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body: %w", err)
 	}
+
+	ch <- int64(len(body))
+	return nil
 }

examples/routine_leak/example2/step2/app_leaking_routine.go

@@ -2,51 +2,83 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"github.com/openshift-online/async-routine"
+	"github.com/openshift-online/async-routine/examples/routine_leak/example2/data"
+	"io"
 	"math/rand"
+	"net/http"
 	"os"
 	"runtime/pprof"
+	"strconv"
 	"time"
 )
 
 func main() {
-	async.
-		NewAsyncRoutine("main-job", context.Background(), doJob).
-		Run()
-
 	for {
-		time.Sleep(4 * time.Second)
+		for i := 0; i < 10; i++ {
+			url := data.Websites[rand.Intn(len(data.Websites))]
+			async.NewAsyncRoutine(
+				"do-job",
+				context.Background(),
+				func() {
+					doJob(url)
+				}).
+				Run()
+			time.Sleep(500 * time.Millisecond)
+		}
 		_ = pprof.Lookup("goroutine").WriteTo(os.Stdout, 1)
 	}
-
 }
 
-func doJob() {
-	for {
-		foo()
-		time.Sleep(50 * time.Millisecond)
-	}
+func doJob(url string) {
+	resultChan := make(chan int64)
+	async.NewAsyncRoutine(
+		"get-website-size",
+		context.Background(),
+		func() {
+			getResponseSize(url, resultChan)
+		}).Run()
+	size := <-resultChan
+	// do something fun with the size - here we just avoid the compilation error
+	size = size
 }
 
-func foo() {
-	bar()
-}
+// GetResponseSize fetches the given URL and sends the response size (in bytes) to the provided channel.
+// Returns an error if the site does not exist or the request fails.
+func getResponseSize(url string, ch chan<- int64) error {
+	// Perform the HTTP request
+	res, err := http.Get(url)
+	if err != nil {
+		return fmt.Errorf("site unreachable: %w", err)
+	}
+	defer res.Body.Close()
 
-func bar() {
-	async.
-		NewAsyncRoutine("parent-go-routine", context.Background(), parentGoroutine).
-		Run()
-}
+	// Handle HTTP errors
+	if res.StatusCode != http.StatusOK {
+		switch res.StatusCode {
+		case http.StatusNotFound:
+			return fmt.Errorf("site does not exist (404 Not Found)")
+		default:
+			return fmt.Errorf("invalid HTTP response: %d %s", res.StatusCode, http.StatusText(res.StatusCode))
+		}
+	}
 
-func parentGoroutine() {
-	async.
-		NewAsyncRoutine("run-command", context.Background(), func() { doInterestingStuff(rand.Intn(100)) }).
-		Run()
-	time.Sleep(500 * time.Millisecond)
-}
+	// Try to use Content-Length header if available
+	if contentLength := res.Header.Get("Content-Length"); contentLength != "" {
+		size, err := strconv.ParseInt(contentLength, 10, 64)
+		if err == nil && size > 0 {
+			ch <- size
+			return nil
+		}
+	}
 
-func doInterestingStuff(value int) {
-	if value%4 == 0 {
-		select {}
+	// Calculate the size by reading the response body
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body: %w", err)
 	}
+
+	ch <- int64(len(body))
+	return nil
 }

examples/routine_leak/example2/step3/README.md

@@ -26,15 +26,29 @@ func main() {
 
 The output will be something like this: 
 ```
-running routine count: 14
-running routine count: 17
-running routine count: 19
-running routine count: 21
-running routine count: 23
-running routine count: 28
-running routine count: 30
-running routine count: 31
-...
+running routine count: 2
+running routine count: 3
+running routine count: 3
+running routine count: 2
+running routine count: 4
+running routine count: 4
+running routine count: 2
+running routine count: 4
+running routine count: 4
+running routine count: 2
+running routine count: 3
+running routine count: 5
+running routine count: 3
+running routine count: 3
+running routine count: 5
+running routine count: 5
+running routine count: 3
+running routine count: 4
+running routine count: 4
+running routine count: 4
+running routine count: 5
+running routine count: 5
+running routine count: 7
 ```
 
 We can see we have a routine leak, but we still have no idea of what is the routine leak.