Select with timeout

Learn to use time.After for a timeout inside select.

select with timeout

With time.After you add a timeout to select. If no case is ready within the duration the timeout case fires. This removes the risk of waiting forever.

Pattern: case <-time.After(2 * time.Second):. This returns a channel that signals after 2 seconds. select waits on it; when the time elapses the timeout case runs and the goroutine exits or does other work.

Timeout pattern

The timeout pattern is critical in production: when sending a request to a service you give up if no response arrives in time. This prevents the system from filling with blocked goroutines.

context.WithTimeout gives a cleaner alternative; it carries the timeout as a context and also signals cancellation. Context is covered in detail in later lessons.

Exercise Wait with a timeout

Inside main, add a select { case ... case <-time.After(...): ... } block and print timeout with fmt.Println.

Show example solution

package main

import "fmt"

func main() {
    ch := make(chan string)
    select {
    case m := <-ch:
        fmt.Println(m)
    default:
        fmt.Println("zaman aşımı")
    }
}

Test yourself

What does time.After return?
- A duration
- A goroutine
- An error
- A channel
Show answer

A channel — a channel. Duration is time.Duration; time.After returns a channel.

Timeout case

select {
case v := <-ch:
    fmt.Println(v)
case <-time.After(____):
    fmt.Println("zaman aşımı")
}

Show answer

select {
case v := <-ch:
    fmt.Println(v)
case <-time.After(2 * time.Second):
    fmt.Println("zaman aşımı")
}

Match timeout concepts

time.After

Timeout
select

Wait
channel

Signal
default

Non-blocking

Next lesson: Closing a channel

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies