golang parallel async tasks, using WaitGroups and Mutex locks

main.go

package main

import (
	"fmt"
	"time"
	"sync"
)

type QueryResult struct {
	key    string
	result string
}

func main() {
	// runs taks in parallel,
	// mutates the "results" map to collect all the results
	start := time.Now()
	queries := map[string]string{
		"a": "...",
		"b": "...",
		"c": "...",
	}
	numQueries := len(queries)
	
	var wg sync.WaitGroup
	wg.Add(numQueries)

	var mu sync.RWMutex
	
	results := map[string]string{}
	
	for key, query := range queries {
		go func(k, q string) {
			defer wg.Done()
			fmt.Printf("Going to query for key %s...\n", k)
			// sleep to mock a long running task
			time.Sleep(time.Duration(2) * time.Second)

			mu.Lock()
			results[k] = "result"
			mu.Unlock()

		}(key, query)
	}
	wg.Wait()

	fmt.Println("collected results:", results)
	fmt.Println("took", time.Since(start))
}