Concurrency

[mtchuyen]

Ref:

• https://blog.devgenius.io/using-goroutines-is-slower-ba99c2fadce9

Concurrent programming is one of the most interesting features Golang has to offer.

• Concurrent xuất hiện dựa trên ý tưởng: đưa các task mất nhiều thời gian để hoàn thành (a long time to run or to complete) vào 1 concurrent khác.

Concurrent dựa trên 2 kỹ thuật của Go:

• GO routine: it consists of a function that runs independently. We can think of it as a process running in another lightweight and cheap thread.
• Channels: they provide a way to communicate between functions running concurrently and to synchronize them if necessary.

GO routines combined with channels provide an easy way of performing independent tasks and communicating between them.

Tác dụng của concurrency

Jacob Kim:

Once you understand the syntax of goroutines and the theory behind concurrency, you feel as if you just gained a superpower.

• Almost case, Concurrency solves the issue of blocking code, so making everything as concurrent as possible will speed things up

Concurrency patterns

Concurrency patterns: các vấn đề problems hay được giải quyết (solve) bởi concurrent.

1. Fan-In Pattern
2. Take First n Values from Stream
3. Subscription Pattern
4. Map pattern
5. Filter pattern

Ref:

• 5 Concurrency Patterns in GO to Enhance your next Project: https://blog.devgenius.io/5-useful-concurrency-patterns-in-golang-8dc90ad1ea61

Go: Concurrency Bugs in Go

https://medium.com/a-journey-with-go/go-concurrency-bugs-in-go-7d3677a1f2a2

[mtchuyen]

How to Implement Concurrency and Parallelism in Go

https://levelup.gitconnected.com/how-to-implement-concurrency-and-parallelism-in-go-83c9c453dd2

Basic of goroutine

https://levelup.gitconnected.com/what-is-a-goroutine-find-the-right-way-to-implement-goroutines-f6ef15d1c32b

Using Goroutines and Wait Groups for Concurrency in Golang

https://medium.com/swlh/using-goroutines-and-wait-groups-for-concurrency-in-golang-78ca7a069d28

[mtchuyen]

How to Broadcast Channels in Go

https://betterprogramming.pub/how-to-broadcast-messages-in-go-using-channels-b68f42bdf32e

Channels are a key component of concurrent programming in Golang. They offer a clean way to communicate between various Go routines.

• They work to synchronize and allow communication between a sender and a receiver.
• A common pattern is to use them to perform a 1 to 1 communication, between a sender and a listener. In some cases, we might want to pass the message from **a channel** to multiple listeners. This behavior is commonly referred as broadcasting***.

However, in Go the same data can only be read once from a channel.

• Nếu có nhiều Go routines are listening to the same channel, due to the random aspect of the runtime scheduler, we cannot predict the exact what routines will catch this data.

Broadcasting Principle

Therefore, to be able to send the same information to multiple listeners, we have two main options:

• Write to the source channel several times, making sure that every listener has received the message.
• Write to the source channel only once, read the data and then replicate it, writing it to each listener individually.

[mtchuyen]

5 Concurrency Patterns in GO to Enhance your next Project

https://blog.devgenius.io/5-useful-concurrency-patterns-in-golang-8dc90ad1ea61

Concurrency Patterns

When a program or an algorithm is concurrent, it means that it is designed to be decomposed into smaller parts that will be executed in independent processes in parallel.

In other words, as Rob Pike said:

“Concurrency is about dealing with lots of things at once. Parallelism is about doing lots of things at once.” Concurrency: nghĩa là xử lý nhiều việc cùng lúc Parallelism: nghĩa là làm nhiều việc cùng lúc

goroutines thường được sử dụng trong Golang. Khi sử dụng goroutines thường sẽ phân làm 2 loại patter: concurrent và Synchronization

• Người ta thường nghĩ tới dùng pattern concurrent khi có sự tranh chấp, tái dùng tài nguyên
• Người ta thường dùng pattern Synchronization khi cần giao tiếp giữa các goroutines và đồng bộ thông tin (communication and synchronization between goroutines)

concurrent thường xử dụng các kỹ thuật:

• Atomic
• Mutex

Synchronization thường sử dụng các kỹ thuật:

• Channels

Concurrency Patterns

• https://go.dev/blog/pipelines
• https://www.calhoun.io/concurrency-patterns-in-go-sync-waitgroup/
• https://blog.logrocket.com/concurrency-patterns-golang-waitgroups-goroutines/

Synchronization patterns in Go

• http://blog.mozo.jp/2014/06/synchronization-patterns-in-go.html

• https://code-pilot.me/post/Synchronization%20patterns%20in%20Go

• https://www.linkedin.com/pulse/concurrency-patterns-go-part-2-miah-md-shahjahan/

• https://dev.to/jolyon129/practical-synchronization-with-go-2nck

• https://medium0.com/@fatbeanli/goroutine-synchronization-patterns-fafe3a35d3e6

• https://www.reddit.com/r/golang/comments/11vtbod/synchronization_patterns_in_go/