publish goroutines

examples.txt

@@ -25,7 +25,7 @@ Maps
 # Interfaces
 # Errors
 # OK Guards
-# Goroutines
+Goroutines
 # Concurrent Goroutines
 # Channels
 # Channel Buffering

examples/goroutines/goroutines.go

@@ -1,15 +1,37 @@
+// A _goroutine_ is a lightweight thread of execution.
+
 package main
 
 import "fmt"
 
-func f(n int) {
-    for i := 0; i < 10; i++ {
-        fmt.Println(n, ":", i)
+func f(from string) {
+    for i := 0; i < 3; i++ {
+        fmt.Println(from, ":", i)
     }
 }
 
 func main() {
-    go f(0)
+
+    // Suppose we have a function call `f(s)`. Here's how
+    // we'd call that in the usual way, running it inline.
+    f("direct")
+
+    // To invoke this function in a goroutine, use
+    // `go f(s)`. This will start a new, concurrently
+    // executing goroutine.
+    go f("goroutine")
+
+    // You can also start a goroutine for an anonymous
+    // function.
+    go func() {
+        fmt.Println("going")
+    }()
+
+    // Since our two goroutines are running asynchrously
+    // in separate goroutines now, execution immediatly
+    // falls through to here. This `Scanln` code requires
+    // that we press a key before the program exits.
     var input string
     fmt.Scanln(&input)
+    fmt.Println("done")
 }

examples/goroutines/goroutines.sh

@@ -0,0 +1,17 @@
+# When we run this program, we see the output of the
+# direct call first, then the interleaved output of the
+# two gouroutines. This interleaving reflects the
+# goroutines being run concurrently by the Go runtime.
+$ go run goroutines.go
+direct : 0
+direct : 1
+direct : 2
+goroutine : 0
+going
+goroutine : 1
+goroutine : 2
+<enter>
+done
+
+# Next we'll look at a complement to goroutines in
+# concurrent Go programs: channels.