How to do concurrency in golang

Go’s CSP concurrency model

Go implements two forms of concurrency. The first is generally recognized by everyone: multi-threaded shared memory. In fact, it is multi-threaded development in languages ​​​​such as Java or C.

Another one is unique to the Go language and recommended by the Go language: the CSP (communicating sequential processes) concurrency model. (Recommended learning: go)

The CSP concurrency model was a concept proposed around 1970. It is a relatively new concept and is different from traditional multi-threads communicating through shared memory. , CSP focuses on "sharing memory through communication."

Please remember the following sentence:

Do not communicate by sharing memory; instead, share memory by communicating.
“不要以共享内存的方式来通信，相反，要通过通信来共享内存。”

Ordinary thread concurrency model is like Java, C, or Python. The communication between threads is through sharing. memory method.

A very typical way is to access shared data (such as an array, Map, or a structure or object) through a lock. Therefore, in many cases, a convenient operation is derived. The data structure is called a "thread-safe data structure".

For example, the data structure in the package "java.util.concurrent" provided by Java. The traditional thread concurrency model is also implemented in Go.

Go’s CSP concurrency model is implemented through goroutine and channel.

goroutine is the concurrent execution unit in the Go language. It's a bit abstract, but it's actually similar to the traditional concept of "thread" and can be understood as "thread".

Channel is the communication mechanism before each concurrent structure (goroutine) in the Go language. In layman's terms, it is the "pipeline" for communication between various goroutines, which is somewhat similar to the pipes in Linux.

The way to generate a goroutine is very simple: Go and it will be generated.

go f();

The communication mechanism channel is also very convenient. Use channel <- data to transmit data and <-channel to retrieve data.

In the communication process, data transmission channel <- data and data retrieval <-channel will inevitably appear in pairs, because there is transmission here and fetching there, only between two goroutines Enable communication.

And regardless of whether it is passed or retrieved, it will be blocked until another goroutine passes or retrieved.

There are two goroutines, one of which initiates a value transfer operation to the channel. (goroutine is a rectangle, channel is an arrow)

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