Context Package in Go – Timeouts, Cancellation, and Best Practices

What is the context Package?

The context package carries deadlines, cancellation signals, and request-scoped values across API boundaries and between goroutines.

Setting a Timeout

ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
defer cancel()

select {
case <-time.After(5 * time.Second):
    fmt.Println("Work finished")
case <-ctx.Done():
    fmt.Println("Timeout:", ctx.Err())
}

Manual Cancellation

ctx, cancel := context.WithCancel(context.Background())

go func() {
    time.Sleep(1 * time.Second)
    cancel() // cancels the context
}()

<-ctx.Done()
fmt.Println("Cancelled:", ctx.Err())

Best Practices

• Always call cancel() (usually via defer) to release resources, even if the operation completes normally.
• Pass context.Context as the first parameter of functions that perform I/O or long-running work.
• Avoid storing large amounts of data in a context — it's meant for small, request-scoped values.