Addressing review comments

* Renamed the example
* Reworded comments
* Moved it to after worker pools
* Sleep for a second instead of random
* Mention the new sample in worker pools

examples.txt

@@ -23,7 +23,6 @@ Goroutines
 Channels
 Channel Buffering
 Channel Synchronization
-Waiting For Goroutines To Finish
 Channel Directions
 Select
 Timeouts
@@ -33,6 +32,7 @@ Range over Channels
 Timers
 Tickers
 Worker Pools
+WaitGroup
 Rate Limiting
 Atomic Counters
 Mutexes

examples/waitgroup/waitgroup.go

@@ -1,27 +1,22 @@
 // To wait for multiple goroutines to finish, we can
-// use a sync.WaitGroup.
+// use a *wait group*.
 
 package main
 
 import (
     "fmt"
-    "math/rand"
     "sync"
     "time"
 )
 
 // This is the function we'll run in every goroutine.
-// wg is the WaitGroup it uses to notify that it's done.
 // Note that a WaitGroup must be passed to functions by
 // pointer.
 func worker(id int, wg *sync.WaitGroup) {
     fmt.Printf("Worker %d starting\n", id)
 
-    // Sleep for a random duration between 500-700 ms
-    // to simulate work. See the [random numbers](random-numbers)
-    // example for more details on *rand*.
-    msToSleep := time.Duration(500 + rand.Intn(200))
-    time.Sleep(msToSleep * time.Millisecond)
+    // Sleep to simulate an expensive task.
+    time.Sleep(time.Second)
     fmt.Printf("Worker %d done\n", id)
 
     // Notify the WaitGroup that we're done.

examples/waitgroup/waitgroup.hash

@@ -0,0 +1,2 @@
+ffc6520e73ebfa2b8c470e3ef00fee55388234e0
+8cD2V9CgI0J

examples/waitgroup/waitgroup.sh

@@ -1,4 +1,4 @@
-$ go run waiting-for-goroutines-to-finish.go
+$ go run waitgroup.go
 Worker 5 starting
 Worker 3 starting
 Worker 4 starting

examples/waiting-for-goroutines-to-finish/waiting-for-goroutines-to-finish.hash

@@ -1,2 +0,0 @@
-f068072d11ed9469174c18f5b7a6a7d9d8d3dafb
-koKzXfbq8kg

examples/worker-pools/worker-pools.go

@@ -12,37 +12,40 @@ import "time"
 // results on `results`. We'll sleep a second per job to
 // simulate an expensive task.
 func worker(id int, jobs <-chan int, results chan<- int) {
-    for j := range jobs {
-        fmt.Println("worker", id, "started  job", j)
-        time.Sleep(time.Second)
-        fmt.Println("worker", id, "finished job", j)
-        results <- j * 2
-    }
+	for j := range jobs {
+		fmt.Println("worker", id, "started  job", j)
+		time.Sleep(time.Second)
+		fmt.Println("worker", id, "finished job", j)
+		results <- j * 2
+	}
 }
 
 func main() {
 
-    // In order to use our pool of workers we need to send
-    // them work and collect their results. We make 2
-    // channels for this.
-    jobs := make(chan int, 100)
-    results := make(chan int, 100)
+	// In order to use our pool of workers we need to send
+	// them work and collect their results. We make 2
+	// channels for this.
+	jobs := make(chan int, 100)
+	results := make(chan int, 100)
 
-    // This starts up 3 workers, initially blocked
-    // because there are no jobs yet.
-    for w := 1; w <= 3; w++ {
-        go worker(w, jobs, results)
-    }
+	// This starts up 3 workers, initially blocked
+	// because there are no jobs yet.
+	for w := 1; w <= 3; w++ {
+		go worker(w, jobs, results)
+	}
 
-    // Here we send 5 `jobs` and then `close` that
-    // channel to indicate that's all the work we have.
-    for j := 1; j <= 5; j++ {
-        jobs <- j
-    }
-    close(jobs)
+	// Here we send 5 `jobs` and then `close` that
+	// channel to indicate that's all the work we have.
+	for j := 1; j <= 5; j++ {
+		jobs <- j
+	}
+	close(jobs)
 
-    // Finally we collect all the results of the work.
-    for a := 1; a <= 5; a++ {
-        <-results
-    }
+	// Finally we collect all the results of the work.
+	// This also ensures that the worker goroutines have
+	// finished. An alternative way to wait for multiple
+	// goroutines is to use a [WaitGroup](waitgroup).
+	for a := 1; a <= 5; a++ {
+		<-results
+	}
 }

examples/worker-pools/worker-pools.hash

@@ -1,2 +1,2 @@
-1f9acf1e50be05cad73e6b085ed3294892c67d42
-RTRcHA05vV
+bfd2824b3840ff67fa9a0218c7be66647b4bf3d9
+IQestAFcxLh

public/channel-synchronization

@@ -171,7 +171,7 @@ started.</p>
       
       
       <p class="next">
-        Next example: <a href="waiting-for-goroutines-to-finish">Waiting For Goroutines To Finish</a>.
+        Next example: <a href="channel-directions">Channel Directions</a>.
       </p>
       
       <p class="footer">

public/index.html

@@ -85,8 +85,6 @@
       
         <li><a href="channel-synchronization">Channel Synchronization</a></li>
       
-        <li><a href="waiting-for-goroutines-to-finish">Waiting For Goroutines To Finish</a></li>
-      
         <li><a href="channel-directions">Channel Directions</a></li>
       
         <li><a href="select">Select</a></li>
@@ -105,6 +103,8 @@
       
         <li><a href="worker-pools">Worker Pools</a></li>
       
+        <li><a href="waitgroup">WaitGroup</a></li>
+      
         <li><a href="rate-limiting">Rate Limiting</a></li>
       
         <li><a href="atomic-counters">Atomic Counters</a></li>

public/worker-pools

@@ -40,7 +40,7 @@ a <em>worker pool</em> using goroutines and channels.</p>
             
           </td>
           <td class="code leading">
-	        <a href="http://play.golang.org/p/RTRcHA05vV"><img title="Run code" src="play.png" class="run" /></a>
+	        <a href="http://play.golang.org/p/IQestAFcxLh"><img title="Run code" src="play.png" class="run" /></a>
             <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
 </pre></div>
 
@@ -147,7 +147,11 @@ channel to indicate that&rsquo;s all the work we have.</p>
         
         <tr>
           <td class="docs">
-            <p>Finally we collect all the results of the work.</p>
+            <p>Finally we collect all the results of the work.
+This also ensures that the worker goroutines have
+finished. An alternative way to wait for multiple
+goroutines that&rsquo;s useful in many scenarios is
+to use a <a href="waitgroup">WaitGroup</a>.</p>
 
           </td>
           <td class="code">
@@ -207,7 +211,7 @@ there are 3 workers operating concurrently.</p>
       
       
       <p class="next">
-        Next example: <a href="rate-limiting">Rate Limiting</a>.
+        Next example: <a href="waitgroup">WaitGroup</a>.
       </p>
       
       <p class="footer">