What is the context in Go? What is it used for? How does timeout cancellation work?

In Go, context is a package and a concept for managing the lifetime of operations, passing cancellation signals, and deadlines between goroutines.

Main tasks of context:

• cancel operations (e.g., on timeout or user cancellation),
• pass values (e.g., request ID) through call chains,
• set deadlines (timeouts).

Timeout cancellation works as follows:

1. A context with a deadline or timeout is created, for example, context.WithTimeout.
2. When the time expires, the context is automatically canceled.
3. The goroutine listening to this context receives a cancellation signal through the Done() channel.
4. The goroutine should handle cancellation properly (e.g., interrupt work and free resources).

Example:

ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()

select {
case <-time.After(3 * time.Second):
    fmt.Println("operation completed")
case <-ctx.Done():
    fmt.Println("operation cancelled or timed out")
}

Here, the operation will be interrupted after 2 seconds if it does not finish earlier.