Example of using go routines as async producer/consumer workers communicating over a channel

workers.go

package main

import (
	"fmt"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"
)

const (
	producerCount                 = 4
	consumerCount                 = 8
	producerFrequency             = 1000 * time.Millisecond
	consumerSimulatedWorkDuration = 2000 * time.Millisecond
	messageChannelSize            = 8
	timestampFormat               = "2006-01-02 15:04:05.000"
)

func main() {
	// Channel for producers to communicate with consumers
	messages := make(chan string, messageChannelSize)

	// Start producer workers
	isProducing := true
	producerGroup := sync.WaitGroup{}
	producerGroup.Add(producerCount)
	for i := 0; i < producerCount; i++ {
		go func(id int) {
			defer producerGroup.Done()
			fmt.Printf("Producer %d started\n", id)
			num := 0
			for isProducing {
				time.Sleep(producerFrequency)
				m := fmt.Sprintf("%d:%d:%s", id, num, time.Now().Format(timestampFormat))
				func() {
					for isProducing {
						select {
						case messages <- m:
							fmt.Printf("Producer %d sent message @ %s, channel length: %d --> %s\n", id, time.Now().Format(timestampFormat), len(messages), m)
							return
						default:
							fmt.Println("Channel full, waiting...")
							time.Sleep(100 * time.Millisecond)
						}
					}
				}()
				num++
			}
			fmt.Printf("Producer %d stopped\n", id)
		}(i)
	}

	// Start consumer workers
	consumerGroup := sync.WaitGroup{}
	consumerGroup.Add(consumerCount)
	for i := 0; i < consumerCount; i++ {
		go func(id int) {
			defer consumerGroup.Done()
			fmt.Printf("Consumer %d started\n", id)
			for m := range messages {
				fmt.Printf("Consumer %d received message @ %s, channel length: %d --> %s\n", id, time.Now().Format(timestampFormat), len(messages), m)
				time.Sleep(consumerSimulatedWorkDuration)
			}
			fmt.Printf("Consumer %d stopped\n", id)
		}(i)
	}

	// Wait for Ctrl+C
	c := make(chan os.Signal)
	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
	<-c

	// Stop producers
	fmt.Println("Stopping producers")
	isProducing = false
	producerGroup.Wait()
	fmt.Println("Stopped producers")

	// Stop consumers (closing the channel will allow them to process any pending messages before they exit)
	fmt.Println("Stopping consumers")
	close(messages)
	consumerGroup.Wait()
	fmt.Println("Stopped consumers")
}