Running out of memory when using node streams

I am trying to index a big (1 500 000 lines) file and push it to elastic search. In order to do this, I am using node js streams; however, I keep running out of memory. What am I doing wrong?

var rl = null;

initialize(function() {
  var stream =  fs.createReadStream(process.argv[2]);
  rl = readline.createInterface({input: stream, terminal: false});
  var i = 0;

  rl.on('line', function(line) {
    rl.pause();
    processObject(++i, extractObject(line));
  });

  rl.on('close', function() {
    console.log('\nRefreshed index;');
    process.exit();
  });
});

function processObject(number, input) {
    client.index({
            index: INDEX,
            type: TYPE,
            id: number,
            body: input
    }, function (error, response) {
        rl.resume();
        if(number % 1000 == 0) process.stdout.write('.');
    });
};