Simple illustration of bug in pausing stream being parsed by node csv

node csv stream bug example.js

var csv = require('csv');
var fs = require('fs');
var os = require('os');
var path = require('path');

var ENABLE_PAUSING = true;

var testFilePath = path.join(os.tmpDir(),'test.csv');

console.log('Creating test csv temp file');

var testFileContents = '';

var numTestRows = 100000;

var i = 0;
while (i < numTestRows*5) {
    testFileContents += [++i, ++i, ++i, ++i, ++i].join(',')+'\n';
}

fs.writeFileSync(testFilePath, testFileContents);

console.log('Reading CSV file');

var stream = fs.createReadStream(testFilePath);
var rowsProcessed = 0;

csv().from.stream(stream)
    .on('record', function(row, index) {
        if (++rowsProcessed % (Math.floor(numTestRows / 5)) === 0) {
            console.log('Processed '+rowsProcessed+' rows so far');
            if (ENABLE_PAUSING) {
                console.log('pausing stream for 100ms--reading should stop');
                if (!stream.paused) {
                    stream.pause();
                    setTimeout(function() {
                        console.log('resuming stream--reading should resume');
                        stream.resume();
                    }, 100);
                }
            }
        }
    })
    .on('end', function() {
        console.log('Read '+rowsProcessed+' rows');
    })
    .on('error', function(error){
        console.log('Error: ', error);
    });