Node.js Readable self.push（）在15次迭代之后停止

我试图理解为什么Readable = require('stream').Readable在这个代码中Readable = require('stream').Readable只能在node.js上运行15次。 我省略这行X.on('data',function() {console.log('data')}); 这条线无限期重复，这是正确的。

start.js

 console.log('Start Therm'); const thermom = require('./therm.js'); var X = new thermom(); X._read(); X.on('start',function() {console.log('start')}); // X.on('data',function() {console.log('data')}); X.on('end',function() {console.log('end')}); X.on('error',function() {console.log('error')}); 

therm.js

 var Readable = require('stream').Readable; var util = require('util'); var _ = require('lodash'); var count=0; function getTemperatureReadingFromThermometer(cb) { setTimeout(function() { cb(null, Math.round(Math.random() * 20 * 100)/100) }, 10); } module.exports = Thermometer; function Thermometer(options) { this.count = 0; if (! (this instanceof Thermometer)) { return new Thermometer(options); } if (! options) { options = {}; } options.objectMode = true; Readable.call(this, options); } util.inherits(Thermometer, Readable); Thermometer.prototype._read = function read() { var self = this; getTemperatureReadingFromThermometer( function(err, temperature) { console.log('getTemperatureReadingFromThermometer :' + temperature ); if (err) { self.emit('error', err); } else { console.log('self.push(temperature) : ' + count++); self.push(); } }); }; 

节点start.js只输出15次迭代。

 Start Therm getTemperatureReadingFromThermometer :7.98 self.push(temperature) : 0 getTemperatureReadingFromThermometer :18.46 self.push(temperature) : 1 getTemperatureReadingFromThermometer :13.27 self.push(temperature) : 2 getTemperatureReadingFromThermometer :1.6 self.push(temperature) : 3 getTemperatureReadingFromThermometer :18.08 self.push(temperature) : 4 getTemperatureReadingFromThermometer :2.08 self.push(temperature) : 5 getTemperatureReadingFromThermometer :10.91 self.push(temperature) : 6 getTemperatureReadingFromThermometer :13 self.push(temperature) : 7 getTemperatureReadingFromThermometer :9.98 self.push(temperature) : 8 getTemperatureReadingFromThermometer :14.4 self.push(temperature) : 9 getTemperatureReadingFromThermometer :6.69 self.push(temperature) : 10 getTemperatureReadingFromThermometer :12.14 self.push(temperature) : 11 getTemperatureReadingFromThermometer :3.65 self.push(temperature) : 12 getTemperatureReadingFromThermometer :13.54 self.push(temperature) : 13 getTemperatureReadingFromThermometer :16.59 self.push(temperature) : 14 getTemperatureReadingFromThermometer :1.69 self.push(temperature) : 15 

任何提示将不胜感激

Answer 1

我终于find了这个窘境的答案。

  var X = new thermom({highWaterMark: 500 }); 

会在这个队列中给你一个500个项目的缓冲区，同样一个5的highWaterMark将迭代次数减less到只有5次。它logging在node.js这里https://nodejs.org/api/stream.html#stream_new_stream_readable_options