What is the difference between a buffered and an unbuffered channel in Go?

Q: What is the difference between a buffered and an unbuffered channel in Go?

Learn the answer to "What is the difference between a buffered and an unbuffered channel in Go?" with detailed explanations, code examples, and best practices on DeployU.

The Scenario

You are a backend engineer at a fintech company. You are writing a new service that needs to communicate between two goroutines. You are not sure whether to use a buffered or an unbuffered channel.

The Challenge

Explain the difference between a buffered and an unbuffered channel in Go. What are the pros and cons of each approach, and which one would you choose for this use case?

Wrong Approach

A junior engineer might think that they are interchangeable. They might not be aware of the performance implications of choosing one over the other.

Addresses symptoms, not root cause

Right Approach

A senior engineer would be able to provide a detailed explanation of the differences between a buffered and an unbuffered channel. They would also be able to explain the trade-offs between each approach and would have a clear recommendation for which one to use in this use case.

Step 1: Understand the Key Differences

Feature	Unbuffered Channel	Buffered Channel
Capacity	Has a capacity of zero.	Has a capacity of one or more.
Blocking	A sender is blocked until a receiver is ready, and a receiver is blocked until a sender is ready.	A sender is blocked only if the buffer is full, and a receiver is blocked only if the buffer is empty.
Use Cases	When you need to synchronize two goroutines.	When you want to decouple the sender and the receiver.

Step 2: Choose the Right Tool for the Job

For our use case, it depends on whether we need to synchronize the two goroutines.

If we need to make sure that the two goroutines are synchronized, we should use an unbuffered channel.
If we want to decouple the two goroutines and allow them to run independently, we should use a buffered channel.

Step 3: Code Examples

Here are some code examples that show the difference between the two approaches:

Unbuffered Channel:

package main

import "fmt"

func main() {
    ch := make(chan int)

    go func() {
        ch <- 1
    }()

    fmt.Println(<-ch)
}

In this example, the main goroutine will be blocked until the other goroutine sends a value to the channel.

Buffered Channel:

package main

import "fmt"

func main() {
    ch := make(chan int, 1)

    ch <- 1

    fmt.Println(<-ch)
}

In this example, the main goroutine will not be blocked, because the channel has a capacity of one.

Systematic, production-ready debugging

Practice Question

You have a sender goroutine that produces data at a faster rate than the receiver goroutine can consume it. Which of the following would be the most appropriate?

Questions