node.js - Nodejs for 循环 - 流内存不足

Question

我正在生成一个想要保存的 CSV 文件。虽然有点大，但是代码很简单。我使用流来防止内存不足错误，但无论如何它都会发生。有什么建议吗？

const fs = require('fs');
var noOfRows = 2000000000;
var stream = fs.createWriteStream('myFile.csv', {flags: 'a'});
for (var i=0;i<=noOfRows;i++){
  var col = '';
  col += i;
  stream.write(col)
}

Answer 1

添加一个drain事件监听器。

const fs = require("fs");
var noOfRows = 2000000000;
var stream = fs.createWriteStream("myFile.csv", { flags: "a" });
var i = 0;

function write() {
  var ok = true;
  do {
    var data = i + "";
    if (i === noOfRows) {
      // last time!
      stream.write(data);
    } else {
      // see if we should continue, or wait
      // don't pass the callback, because we're not done yet.
      ok = stream.write(data);
    }
    i++;
  } while (i<=noOfRows && ok);
  if (i < noOfRows) {
    // had to stop early!
    // write some more once it drains
    stream.once("drain", write);
  }
}

write();

而且 noOfRows 太大，可能会导致您的 .csv 文件大小超出磁盘大小