代码如下

发现 save() 的回调很久才会被调用，命令行 mongo，db.find() 发觉数据增长超级慢，调用了 200+ 次，才有 10，20 条数据被保存下来

发现了 在 stream.pipe() 这个方法的回调里，如果有其他的回调，处理都很慢，有什么方法解决呢？

let save = function(array) {
  return new Promise(function(resolve, reject) {
    console.log('will save books')
    Book.save(array, function (err, list) {
      if (err) {
        console.log('Fail')
        resolve()
      } else {
        console.log('Save 100')
        reslove()
      }
    })
  })
}

co(function*(){
  yield conn()
  yield sentStream()

  let stream = yield isbnStream()
  
  let count = 0
  let array = []
  stream.pipe(es.mapSync(function (data) {
    delete data.score
    delete data._id
    count += 1
    let isbn = data['isbn']
    let title = data['title']
    let comments = data['comments']
    let reviews = data['reviews']

    if (comments.length < 1 && reviews.length < 1)
      return
        
    let objectList = comments.concat(reviews)
    console.log('Count: ' + count + ' Title: ' + title)

    let finalScore = scoreSentences(objectList)
  
    let book = new Book(data) 
    book.score = finalScore
    array.push(book)
    if (array.length % 1 === 0) {
      save(array)
      array = []
    }
  }))
})