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The main content of this article is to explain "what is the reason for the high concurrency of node". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "what is the reason for the high concurrency of node?"

Because node has the characteristics of "transaction-driven" and asynchronous "Icano", it is a non-blocking asynchronous operation; for each concurrent request, the server registers a firing event to the request, and gives a callback function, which executes event processing sequentially, executes the callback function after processing is completed, and then executes the next event handling, so node can have high concurrency.

Operating environment of this tutorial: windows10 system, nodejs version 12.19.0, Dell G3 computer.

Why can node have high concurrency

Nodejs is a non-blocking asynchronous operation. For each concurrent request, the server registers the request with a trigger event (Imap O) and gives a callback function (this process does not block new connection requests). Event processing is executed sequentially (Iamp O), and after processing is completed, a callback function is executed, followed by the next event processing (Iamp O).

Before explaining why node can achieve high concurrency, take a look at a few other features of node:

Single thread

Let's first clarify the concept that node is single-threaded, which is the same as JavaScript in browsers, and that JavaScript main threads cannot share state with other threads (such as I / O threads) in node.

The benefits of single threading are:

There is no need to pay attention to state synchronization between threads like multithreading.

Without the overhead of thread switching

No deadlock exists

Of course, single threading also has many disadvantages:

Unable to make full use of multicore CPU

Consuming CPU for a large amount of computing will cause application blocking (that is, not suitable for CPU-intensive)

Errors will cause the entire application to exit.

Asynchronous IPUBO

You might ask, since node is single-threaded and events are all handled on a single thread, shouldn't it be inefficient and contrary to high concurrency?

On the contrary, node has high performance. One of the reasons is that node has an asynchronous I / O feature, and node provides an I / O thread to the request whenever an I / O request occurs. Node then ignores the operation of IWeiO and continues to execute events on the main thread, only to be processed when the request returns a callback. That is, node saves a lot of time waiting for a request.

This is also one of the important reasons why node supports high concurrency.

In fact, the vast majority of node operations are done in this asynchronous manner, not just the Istroke O operation. It is like an organizer, it does not need to be hands-on, it only needs to tell members how to operate correctly and accept feedback and handle key steps to make the whole team run efficiently.

Transaction driven

You may have to ask again, how does node know that the request has returned callbacks, and when should it handle them?

The answer is another feature of node: transaction-driven, that is, the main thread runs the program by triggering the event loop event loop.

This is another important reason why node supports high concurrency.

At this point, I believe you have a deeper understanding of "what is the reason why node can have high concurrency?" you might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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