Rate Limiting API Requests Using a Buffered Channel
Owner: SnippetBot
Created: 2026-10-25 00:00:24
Size: 1.66 KB
Expires: Never
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package main
import (
"fmt"
"sync"
"time"
)
// apiCall simulates an external API request
func apiCall(requestID int) string {
fmt.Printf("[%s] Making API call for request %d
", time.Now().Format("15:04:05.000"), requestID)
time.Sleep(time.Millisecond * 100) // Simulate network latency/API processing time
return fmt.Sprintf("Response for request %d", requestID)
}
// NewRateLimiter creates a new rate limiter that allows a burst of 'burst' requests
// and then limits requests to 'rate' per 'period'.
func NewRateLimiter(rate int, period time.Duration, burst int) chan struct{} {
limiter := make(chan struct{}, burst)
// Fill the limiter initially to allow for burst
for i := 0; i < burst; i++ {
limiter <- struct{}{}
}
// Start a goroutine to refill the limiter at the specified rate
go func() {
ticker := time.NewTicker(period / time.Duration(rate))
defer ticker.Stop()
for range ticker.C {
select {
case limiter <- struct{}{}:
// Token added
default:
// Limiter is full (burst capacity reached), do nothing
}
}
}()
return limiter
}
func main() {
// Configure rate limiter: 5 requests per second, with a burst of 10
rateLimiter := NewRateLimiter(5, time.Second, 10)
const numRequests = 20
var wg sync.WaitGroup
fmt.Printf("Attempting to make %d API requests with a rate limit of 5/s and burst of 10.
", numRequests)
for i := 1; i <= numRequests; i++ {
wg.Add(1)
go func(reqID int) {
defer wg.Done()
// Block until a token is available
<-rateLimiter
response := apiCall(reqID)
fmt.Printf("[%s] Received: %s
", time.Now().Format("15:04:05.000"), response)
}(i)
}
wg.Wait()
fmt.Println("All requests completed.")
}