How to Effectively Limit Concurrent Go Routines with Channels?

Limiting the Number of Concurrent Go Routines

When working with a list of URLs that need to be processed asynchronously, it's often desirable to limit the number of concurrent goroutines to prevent overwhelming resources. The solution involves creating a bounded channel that controls the maximum number of goroutines that can execute simultaneously.

Original Attempt

In the original attempt, a buffered channel of size parallel was created:

<code class="go">results := make(chan string, *parallel)</code>

The intention was that when the results channel was full, the program would block until a value was read from the channel, allowing another goroutine to be spawned. However, this approach doesn't limit the number of goroutines effectively, as the main program doesn't block when all URLs have been processed.

Solution

A more effective solution involves creating a fixed number of worker goroutines:

<code class="go">for i := 0; i < *parallel; i++ {
    wg.Add(1)
    go func() {
        defer wg.Done()
        for url := range urls {
            worker(url, client, results)
        }
    }()
}</code>

In this solution, goroutines are responsible for fetching URLs from a channel and processing them. The channel is fed with URLs from a feeder goroutine, and once all URLs are retrieved, the feeder goroutine closes the channel, signaling to the workers to finish their tasks.

A separate goroutine monitors the completion status of the worker goroutines, closing the results channel when all workers are done. This approach effectively limits the number of running goroutines to the specified parallel count.

The above is the detailed content of How to Effectively Limit Concurrent Go Routines with Channels?. For more information, please follow other related articles on the PHP Chinese website!