How to Properly Close Channels After All Goroutines Finish in Go?

Managing Channel Closure for Completed Goroutines in Go

In Go, managing channel closure after all goroutines have completed can be a challenge. This article explores common approaches and provides a solution using sync.WaitGroup.

Problem:
When multiple goroutines send data to a channel, ensuring the channel is appropriately closed to prevent data loss is crucial. Waiting for all goroutines to complete before closing the channel is the desired behavior.

Initial Approach:
One common attempt is to close the channel immediately after spawning all goroutines. However, this can lead to goroutines attempting to send results to a closed channel.

Counting Goroutines:
A more sophisticated approach involves counting running goroutines and closing the channel when the count reaches zero. While this method addresses the issue, it introduces potential synchronization errors.

sync.WaitGroup Solution:
The recommended solution utilizes the sync.WaitGroup type, which simplifies synchronization in concurrent Go programs. By using a WaitGroup, you can easily track the number of goroutines and wait for them to complete before closing the channel.

Code Example:
Here's how to modify the original code using sync.WaitGroup:

var wg sync.WaitGroup
for i := 0; i <= 10; i++ {
    wg.Add(1)
    go func(){
        result := calculate()
        c <- result
        wg.Done()
    }()
}

// Close the channel when all goroutines are finished
go func() {
    wg.Wait()
    close(c)
}()

for result := range c {
    all_result = append(all_result, result...)
}

Here, WaitGroup is used to count the goroutines. Each goroutine increments the count before sending data to the channel and decrements it when finished. A separate goroutine waits for the count to reach zero, ensuring the channel is closed only after all goroutines have completed.

The above is the detailed content of How to Properly Close Channels After All Goroutines Finish in Go?. For more information, please follow other related articles on the PHP Chinese website!