GoLang之Concurrency協程goroutine使用方法

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

2013-12-08 wcdj

在go語言中，使用goroutine（a lightweight thread managed by the Go runtime）來實現並發程式。

go f(x, y, z)

starts a new goroutine running

f(x, y, z)

The evaluation of f, x, y, and z happens in the current goroutine and the execution off happens in the new goroutine.

Goroutines run in the same address space, so access to shared memory must be synchronized. Thesync package provides useful primitives, although you won't need them much in Go as there are other primitives. (See the next slide, Channels.http://tour.golang.org/#64)

簡單的測試案例：

package mainimport ("fmt""time")func main() {// A goroutine is a lightweight thread managed by the Go runtime//  Goroutines run in the same address space, so access to shared memory must be synchronizedgo say("world")say("hello")fmt.Println("---------------1")a := []int{7, 2, 8, -9, 4, 0}// Channels are a typed conduit through which you can send and receive values with the channel operator, <-// By default, sends and receives block until the other side is ready. This allows goroutines to synchronize without explicit locks or condition variablesc := make(chan int)go sum(a[:len(a)/2], c)go sum(a[len(a)/2:], c)x, y := <-c, <-c // receive from cfmt.Println(x, y, x+y)fmt.Println("---------------2")// Channels can be buffered. Provide the buffer length as the second argument to make to initialize a buffered channelc2 := make(chan int, 2)c2 <- 1c2 <- 2//c2 <- 3// error, the send buffer is full that will causes deadlock!fmt.Println(<-c2)fmt.Println(<-c2)//fmt.Println(<-c2)// error, the receive buffer is empty that will causes deadlock too!fmt.Println("---------------3")c3 := make(chan int, 10)go fibonacci(cap(c3), c3)for i := range c3 {fmt.Println(i)}fmt.Println("---------------4")c4 := make(chan int)quit := make(chan int)go func() {for i := 0; i < 10; i++ {fmt.Println(<-c4)}quit <- 0}()fibonacci2(c4, quit)fmt.Println("---------------5")// The default case in a select is run if no other case is ready// Use a default case to try a send or receive without blockingtick := time.Tick(100 * time.Millisecond)boom := time.After(500 * time.Millisecond)for {select {case <-tick:fmt.Println("tick. ")case <-boom:fmt.Println("BOOM!")returndefault:fmt.Println("    .")time.Sleep(50 * time.Millisecond)}}}func say(s string) {for i := 0; i < 5; i++ {time.Sleep(100 * time.Millisecond)fmt.Println(s)}}func sum(a []int, c chan int) {sum := 0for _, v := range a {sum += v}c <- sum // send sum to c}func fibonacci(n int, c chan int) {x, y := 0, 1for i := 0; i < n; i++ {c <- xx, y = y, x+y}// Note: Only the sender should close a channel, never the receiver. Sending on a closed channel will cause a panic// Another note: Channels aren't like files; you don't usually need to close them. Closing is only necessary when the receiver must be told there are no more values coming, such as to terminate a range loopclose(c)}// The select statement lets a goroutine wait on multiple communication operations// A select blocks until one of its cases can run, then it executes that case. It chooses one at random if multiple are readyfunc fibonacci2(c, quit chan int) {x, y := 0, 1for {select {case c <- x:x, y = y, x+ycase <-quit:fmt.Println("quit")return}}}/*output:helloworldhelloworldhelloworldhelloworldhello---------------1world17 -5 12---------------212---------------30112358132134---------------40112358132134quit---------------5    .    .tick.     .    .tick.     .    .tick.     .    .tick.     .    .BOOM!*/