How to Add a Timeout to WaitGroup.Wait() in Go?

Tired of Waiting Forever? Adding a Timeout to WaitGroup.Wait()

When you employ WaitGroup.Wait() to synchronize goroutines and ensure they finish executing, you may occasionally desire the ability to terminate waiting after a specific duration. This prevents your system from endlessly relying on errant workers that may never complete their tasks.

A Pragmatic Solution for Timed WaitGroups

One approach to implementing a timeout involves utilizing a combination of goroutines, channels, and the time package. The idea is to create a channel that receives a signal upon the completion of all goroutines. Simultaneously, a timer is initialized with the desired timeout duration. A select statement is used to monitor both the channel and the timer:

import (
    "sync"
    "time"
)

func task(wg *sync.WaitGroup) {
    // Perform some task...
    time.Sleep(time.Second * 2)
    wg.Done()
}

func main() {
    var wg sync.WaitGroup
    wg.Add(2)
    go task(&wg)
    go task(&wg)

    ch := make(chan struct{})
    defer close(ch)

    go func() {
        defer wg.Done()
        wg.Wait()
        close(ch)
    }()

    timeout := 5*time.Second

    select {
    case <-ch:
        fmt.Println("All jobs completed within timeout.")
    case <-time.After(timeout):
        fmt.Println("Timeout reached, not all jobs completed.")
    }
}

Simplifying the Timeout with Helper Functions

To offer a more convenient and reusable approach, consider creating a helper function that encapsulates this functionality:

func waitTimeout(wg *sync.WaitGroup, timeout time.Duration) bool {
    c := make(chan struct{})
    go func() {
        defer close(c)
        wg.Wait()
    }()
    select {
    case <-c:
        return false
    case <-time.After(timeout):
        return true
    }
}

This helper function accepts a WaitGroup and a desired timeout duration and returns whether or not the wait exceeded the specified limit.

Usage of the Helper Function

Utilizing the helper function is straightforward:

if waitTimeout(&wg, 5*time.Second) {
    fmt.Println("Timeout reached waiting for wait group.")
}

In this example, the waitTimeout function returns true if the wait group takes longer than 5 seconds to complete, indicating that a timeout has occurred.

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