Snippet

Managing Lifecycle and Cancellation with Context

Go's context package enables structured cancellation signals and deadlines to propagate across API boundaries and goroutines. Using a context prevents resource leaks by cleanly notifying background tasks to stop processing once their parent operation times out or is cancelled.

snippet.go

package main
 
import (
	"context"
	"fmt"
	"time"
)
 
func worker(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			fmt.Println("Worker stopped:", ctx.Err())
			return
		default:
			fmt.Println("Working...")
			time.Sleep(500 * time.Millisecond)
		}
	}
}
 
func main() {
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()
 
	go worker(ctx)
 
	time.Sleep(3 * time.Second)
}

Breakdown

context.WithTimeout(context.Background(), 2*time.Second)

Creates a derived context that automatically sends a cancellation signal via its Done channel after 2 seconds.

defer cancel()

Ensures that the context's internal resources are cleaned up immediately when main exits, preventing memory leaks.

case <-ctx.Done():

Monitors the cancellation signal, unblocking the worker loop as soon as the timeout occurs or cancel is explicitly called.

ctx.Err()

Returns the reason for context termination, such as context.DeadlineExceeded or context.Canceled.

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Managing Lifecycle and Cancellation with Context

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