Propagating Cancellation to Downstream Goroutines with Context
Owner: SnippetBot
Created: 2026-08-02 00:00:46
Size: 1.56 KB
Expires: Never
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package main
import (
"context"
"fmt"
"time"
)
// worker simulates an operation that needs to be cancelable.
func worker(ctx context.Context, id int, dataCh <-chan string) {
fmt.Printf("Worker %d: Starting
", id)
for {
select {
case <-ctx.Done():
fmt.Printf("Worker %d: Context cancelled. Shutting down.
", id)
return
case data, ok := <-dataCh:
if !ok {
fmt.Printf("Worker %d: Data channel closed. Shutting down.
", id)
return
}
fmt.Printf("Worker %d: Processing data: %s
", id, data)
// Simulate some work
time.Sleep(500 * time.Millisecond)
}
}
}
func main() {
// Create a context that can be cancelled.
ctx, cancel := context.WithCancel(context.Background())
defer cancel() // Ensure cancellation if main exits early
dataChannel := make(chan string)
// Start a few workers
go worker(ctx, 1, dataChannel)
go worker(ctx, 2, dataChannel)
// Simulate sending some data
go func() {
for i := 0; i < 5; i++ {
select {
case <-ctx.Done():
fmt.Println("Producer: Context cancelled. Stopping data generation.")
return
case dataChannel <- fmt.Sprintf("message-%d", i):
fmt.Printf("Producer: Sent message-%d
", i)
}
time.Sleep(200 * time.Millisecond)
}
// Close the channel when done sending data
close(dataChannel)
fmt.Println("Producer: Data channel closed.")
}()
// Let the workers run for a bit
time.Sleep(2 * time.Second)
fmt.Println("Main: Sending cancellation signal...")
cancel() // Cancel the context
// Give workers time to shut down
time.Sleep(1 * time.Second)
fmt.Println("Main: Exiting.")
}