1 files changed, 54 insertions, 0 deletions
diff --git a/src/pkg/sync/example_test.go b/src/pkg/sync/example_test.go
new file mode 100644
index 000000000..156492400
--- /dev/null
+++ b/src/pkg/sync/example_test.go
@@ -0,0 +1,54 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sync_test
+
+import (
+	"fmt"
+	"net/http"
+	"sync"
+)
+
+// This example fetches several URLs concurrently,
+// using a WaitGroup to block until all the fetches are complete.
+func ExampleWaitGroup() {
+	var wg sync.WaitGroup
+	var urls = []string{
+		"http://www.golang.org/",
+		"http://www.google.com/",
+		"http://www.somestupidname.com/",
+	}
+	for _, url := range urls {
+		// Increment the WaitGroup counter.
+		wg.Add(1)
+		// Launch a goroutine to fetch the URL.
+		go func(url string) {
+			// Fetch the URL.
+			http.Get(url)
+			// Decrement the counter.
+			wg.Done()
+		}(url)
+	}
+	// Wait for all HTTP fetches to complete.
+	wg.Wait()
+}
+
+func ExampleOnce() {
+	var once sync.Once
+	onceBody := func() {
+		fmt.Printf("Only once\n")
+	}
+	done := make(chan bool)
+	for i := 0; i < 10; i++ {
+		go func() {
+			once.Do(onceBody)
+			done <- true
+		}()
+	}
+	for i := 0; i < 10; i++ {
+		<-done
+	}
+	// Output:
+	// Only once
+}