深入理解Go高级并发模式编写更高效可扩展的应用程序

package main

import (
 "fmt"
 "time"
)

func sayHello() {
 fmt.Println("Hello from a goroutine!")
}

func main() {
 go sayHello() // This starts a new goroutine.
 time.Sleep(1 * time.Second) // Give goroutine some time to execute.
}

package main

import "fmt"

func main() {
 message := make(chan string) // create a new channel

 go func() { // start a goroutine
  message <- "Hello from the other side!" // send a message to the channel
 }()

 msg := <-message // receive a message from the channel
 fmt.Println(msg)
}

package main
import (
 "fmt"
 "time"
)
func main() {
 ch1 := make(chan string)
 ch2 := make(chan string)
 go func() {
  for {
   ch1 <- "from ch1"
   time.Sleep(2 * time.Second)
  }
 }()
 go func() {
  for {
   ch2 <- "from ch2"
   time.Sleep(3 * time.Second)
  }
 }()
 go func() {
  for {
   select {
   case msg1 := <-ch1:
    fmt.Println(msg1)
   case msg2 := <-ch2:
    fmt.Println(msg2)
   }
  }
 }()
 select {} // keep the main function alive
}

package main
import (
 "fmt"
 "time"
)
func worker(id int, jobs <-chan int, results chan<- int) {
 for j := range jobs {
  fmt.Println("worker", id, "processing job", j)
  time.Sleep(time.Second)
  results <- j * 2
 }
}
func main() {
 const numJobs = 5
 jobs := make(chan int, numJobs)
 results := make(chan int, numJobs)
 // start 3 workers
 for w := 1; w <= 3; w++ {
  go worker(w, jobs, results)
 }
 // send jobs
 for j := 1; j <= numJobs; j++ {
  jobs <- j
 }
 close(jobs)
 // collect results
 for a := 1; a <= numJobs; a++ {
  <-results
 }
}