Buffered channel

Learn buffered channels and the capacity concept.

Buffered channel

A buffered channel holds a fixed number of values in a buffer: ch := make(chan int, 3). The sender does not block until the buffer is full; sends complete even without a receiver.

When the buffer is full the sender blocks; when empty the receiver blocks. This improves throughput in producer-consumer patterns. But a large buffer can make ordering unclear.

Buffer behavior

Buffered channel behavior boils down to four points:

Sender does not block until buffer is full; no receiver needed yet
Receiver blocks when buffer is empty; it waits for data
cap(ch) gives the buffer size, the total capacity
len(ch) gives the filled slot count, pending data

A buffered channel gives asynchronous starts but no ordering guarantee; choose the size carefully.

Exercise Use a buffered channel

Inside main, add a make(chan string, 2) call and print buffered ran with fmt.Println.

Show example solution

package main

import "fmt"

func main() {
    ch := make(chan string, 2)
    ch <- "tamponlu çalıştı"
    fmt.Println(<-ch)
}

Test yourself

How many values can make(chan int, 3) buffer?
- 2
- 1
- 3
- Unlimited
Show answer

3 — The buffer size is the second argument.

Creating a buffered channel

ch := make(chan int, ____)

Show answer

ch := make(chan int, 3)

Match buffered channel

make(chan int, 3)

Buffered
cap(ch)

Buffer size
len(ch)

Filled count
block

When full

Next lesson: Summary - Channels

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