What is a WaitGroup in Go and how do I use it?

What is a WaitGroup in Go and how do I use it?

A WaitGroup in Go is a synchronization primitive that helps wait for a collection of goroutines to finish executing.

Can you show me a simple example of how to implement a WaitGroup?

Sure! Here's a basic example:

package main

import (
    "fmt"
    "sync"
)

func main() {
    var wg sync.WaitGroup

    for i := 1; i <= 3; i++ {
        wg.Add(1) // Increment the WaitGroup counter
        go func(i int) {
            defer wg.Done() // Decrement the counter when the goroutine completes
            fmt.Printf("Goroutine %d is running\n", i)
        }(i)
    }

    wg.Wait() // Block until the counter is zero
    fmt.Println("All goroutines finished.")
}

This code starts three goroutines and waits for them to finish.

What happens if I forget to call Done()?

If you forget to call Done(), the WaitGroup's counter will never reach zero, causing the main goroutine to block indefinitely at the Wait() call.

Are there any common mistakes to avoid when using WaitGroups?

Yes, some common mistakes include calling Done() multiple times, not calling Add() before starting goroutines, and using WaitGroups across multiple functions without proper synchronization.