How to create and use worker pools - learning about goroutines + channels

worker_pools_demo.go

package main

/**
 * Each worker calculates fibonacci sequence for N int in order to show how worker pools can be utilized.
 *
 * Instructions:
 * UNCOMMENT `DemoCreateSingleWorker()` OR `DemoCreateOneWorkerPerCPUCore()`
 * FOR BEST RESULTS, ONLY UNCOMMENT ONE AT A TIME
 *
 * BE WARNED THIS CAN GET PRETTY INTENSE ON YOUR CPU AFTER LIKE 2 MIN
 */

import (
	"fmt"
	"runtime"
)

func main() {
	totalJobs := 100
	jobsPipe := make(chan int, totalJobs)
	resultsPipe := make(chan int, totalJobs)

	DemoCreateSingleWorker(jobsPipe, resultsPipe, totalJobs)
	// DemoCreateOneWorkerPerCPUCore(jobsPipe, resultsPipe, totalJobs)
}

// fibonacci implemented terribly
func fib(n int) int {
	if n <= 1 {
		return n
	}
	return fib(n-1) + fib(n-2)
}

// worker defines our worker func. as long as there is a job in the
// queue we continue to pick up  the 'next' job
func worker(jobs <-chan int, results chan<- int) {
	for n := range jobs {
		results <- fib(n)
	}
}

// fillQueue fills up our jobs channel
func fillQueue(jobs chan<- int, numJobs int) {
	for i := 0; i < numJobs; i++ {
		jobs <- i
	}
}

// takeJobFromQueueAndDo takes a job off the 'stack' and invokes it (idk if that's proper terminology?)
func takeJobFromQueueAndDo(results <-chan int, numJobs int) {
	for j := 0; j < numJobs; j++ {
		fmt.Printf("Taking job %d\n", j)
		fmt.Println(<-results)
	}
}

// DemoCreateOneWorkerPerCPUCore creates as many workers as there are CPU cores on the current machine
func DemoCreateOneWorkerPerCPUCore(jobs chan int, results chan int, numJobs int) {
	defer close(jobs)
	// Create as many workers as there are CPU cores on the current machine
	for i := 0; i < runtime.NumCPU(); i++ {
		go worker(jobs, results)
	}
	fillQueue(jobs, numJobs)
	takeJobFromQueueAndDo(results, numJobs)
}

// DemoCreateSingleWorker creates one worker to pick jobs off the queue
func DemoCreateSingleWorker(jobs chan int, results chan int, numJobs int) {
	defer close(jobs)
	go worker(jobs, results)
	fillQueue(jobs, numJobs)
	takeJobFromQueueAndDo(results, numJobs)
}