Javascript 在NodeJs中，stream读取是一个消费进程吗

stream是一个抽象接口，用于在Node.js中处理流数据.Node:Stream模块提供了实现流接口的API.

当我学习NodeJS streams时，我遇到了一些问题，我不确定流是否是消耗进程

例如，我有一个公共代码:

import { Readable } from 'stream'

class MyCustomReadableStream extends Readable {
  constructor() {
    super();
    this.data = ['data1', 'data2', 'data3'];
  }

  _read() {
    const chunk = this.data.shift();

    if (chunk) {
      this.push(chunk);
    } else {
      this.push(null);
    }
  }
}

不同代码处理stream有一些不同的情况

情景1:

import { createServer } from "http";

const customStream = new MyCustomReadableStream();

customStream.on('data', (chunk) => {
  console.log('Received chunk of data:', chunk.toString());
});

customStream.on('end', () => {
  console.log('Custom stream reading is complete.');
});


createServer().listen(0)

/*
// Output: 
Received chunk of data: data1
Received chunk of data: data2
Received chunk of data: data3
Custom stream reading is complete.
*/

情景2:

import { createServer } from "http";

const customStream = new MyCustomReadableStream();

setTimeout(() => {
    customStream.on('data', (chunk) => {
        console.log('1Received chunk of data:', chunk.toString());
    });
}, 1000)

customStream.on('end', () => {
  console.log('Custom stream reading is complete.');
});


createServer().listen(0)

/*
// output:
1Received chunk of data: data1
1Received chunk of data: data2
1Received chunk of data: data3
Custom stream reading is complete.
*/

情况3:

import { createServer } from "http";

const customStream = new MyCustomReadableStream();

customStream.on('data', (chunk) => {
  console.log('Received chunk of data:', chunk.toString());
});

setTimeout(() => {
    customStream.on('data', (chunk) => {
        console.log('1Received chunk of data:', chunk.toString());
    });
}, 1000)

customStream.on('end', () => {
  console.log('Custom stream reading is complete.');
});


createServer().listen(0)

/*
// output:
Received chunk of data: data1
Received chunk of data: data2
Received chunk of data: data3
Custom stream reading is complete.
*/

情景4:

import { createServer } from "http";

const customStream = new MyCustomReadableStream();

customStream.on('data', (chunk) => {
  console.log('Received chunk of data:', chunk.toString());
});

customStream.on('data', (chunk) => {
    console.log('1Received chunk of data:', chunk.toString());
});

customStream.on('end', () => {
  console.log('Custom stream reading is complete.');
});


createServer().listen(0)

/*
// output:
Received chunk of data: data1
1Received chunk of data: data1
Received chunk of data: data2
1Received chunk of data: data2
Received chunk of data: data3
1Received chunk of data: data3
Custom stream reading is complete.
Custom stream reading is complete.
*/

我不明白这四种形式的区别，流阅读是一个消费过程吗？