Quickly understand the performance indicators in Node.js

This article will take you through the performance indicators of Node.js, I hope it will be helpful to you!

For us front-end engineers, mastering Node.js application development is the only way for us to become senior/experts. In addition, Node.js is a server-side language. We must not only be able to complete development tasks, but also pay attention to server performance. [Recommended study: "nodejs Tutorial"]

This article will give some preliminary introduction to the basics and performance indicators of Node.js.

Application scenarios

Before introducing NodeJS performance indicators, let’s first take a look at its application scenarios. For different application scenarios, the performance indicators to focus on are Something different.

• BFFThe middle layer, the proxy of the interface, acts as the gateway layer

• Development and build toolgulp, webpackBased on Node.js

• Desktop applicationElectron combined with Node.js

• SSRServer-side rendering

If Node.js is used for the front-end SSR, then CPU and Network will become the main performance bottleneck;

If you use NodeJS to perform data persistence related work, thenI/Oand Disk will have a high occupancy rate;

In most scenarios, CPU, Memory and NetworkIt can be said to be the main performance bottleneck of Node.

Advantages and Disadvantages

• node.js is fault-tolerant and its performance is not very good

• node.js operation database is not professional

• node.js is strong in handling asynchronous io

• io-intensive, not suitable for cpu-intensive

Event loop (libuv)

Here is a picture quoted from the official website, showing a simplified overview of the event loop operation sequence

Phase description

• Timer: This stage executes the scheduling callback functions that have been setTimeout() and setInterval().
• Pending callback: I/O callback whose execution is delayed until the next loop iteration.
• idle, prepare: Only used internally by the system.
• Polling: retrieves new I/O events; executes I/O-related callbacks (in almost all cases, except for shutdown callbacks, those driven by timers and setImmediate() Except for scheduling), in other cases node will block here at the appropriate time.
• Detection: setImmediate() The callback function is executed here.
• Closed callback function: Some closed callback functions, such as: socket.on('close', ...)

V8 GC mechanism

We know that Node.js® is a JavaScript runtime environment based on Chrome V8 engine, and it is single-threaded.

V8 memory is divided into new generation and old generation:

New generation: Using from space->to space memory recycling scavenge algorithm

Old generation: Memory recycling in the form of reference marking and defragmentation

If the GC time is too long, it will cause the js thread to be blocked and affect service performance. Improper use of memory will cause memory overflow. After understanding the above basic knowledge of Node.js, let's look at the performance indicators

Performance indicators

We describe a performance indicator from the system level and the Node.js process level

System level

physical machines, virtual machines, Docker, etc. ) level, providing the following monitoring indicators:

• Memory usage

• ##CPU

  Usage rate

System load, number of processes in use/waiting for progress
System
• QPS

Hard Performance Indicators
Disk Usage
• GC

  Statistics

  ##… …

For each Node.js process, the following monitoring indicators are provided:

• Memory statistics occupied by each memory space in the heap

• Garbage collection (GC) accounts for the proportion of the entire process running time

• QPS

• ##CPU statistics based on 1s, 15s, 30s, and 60s

• libuv handle, timer statistics

• ......

• How to obtain

How do we obtain the performance indicators mentioned above?

System level

System-level indicators can be obtained in the following two ways

const os = requie('os')

//该方法返回 Node.js 进程的内存使用情况的对象
process.memoryUsage()

{
  rss: 4935680,
  heapTotal: 1826816,
  heapUsed: 650472,
  external: 49879
}复制代码

const heapdump = require('heapdump')

heapdump.writeSnapshot('./' + Date.now() + '.heapsnapshot');

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