Limiting Concurrent Goroutines with a Channel Semaphore
Owner: SnippetBot
Created: 2026-09-06 00:00:34
Size: 1.02 KB
Expires: Never
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package main
import (
"fmt"
"sync"
"time"
)
// worker simulates a task that takes some time
func worker(id int, semaphore chan struct{}, wg *sync.WaitGroup) {
defer wg.Done()
// Acquire a slot from the semaphore
semaphore <- struct{}{}
fmt.Printf("Worker %d: Acquired semaphore, starting task...
", id)
// Simulate work
time.Sleep(time.Duration(2 + (id % 3)) * time.Second) // 2, 3, or 4 seconds
fmt.Printf("Worker %d: Task finished.
", id)
// Release the slot back to the semaphore
<-semaphore
}
func main() {
const maxConcurrency = 3
const totalTasks = 10
// Create a buffered channel to act as a semaphore
// Its capacity limits the number of concurrent goroutines
semaphore := make(chan struct{}, maxConcurrency)
var wg sync.WaitGroup
fmt.Printf("Main: Starting %d tasks with a maximum concurrency of %d.
", totalTasks, maxConcurrency)
for i := 1; i <= totalTasks; i++ {
wg.Add(1)
go worker(i, semaphore, &wg)
}
wg.Wait() // Wait for all workers to complete
fmt.Println("Main: All tasks completed.")
}