nodejs的异步处理问题

mongoose = require('mongoose'),
async = require('async'),
ThrowSku = mongoose.model('ThrowSku'),

var importCount = 0;
var throwSkus = req.body.throwSkus;

#######1、先全部执行完毕#########
throwSkus.forEach(function (throwSku) {
var throwSkuSchema = new ThrowSku({
skuId: throwSku.skuId,
stockGroup: throwSku.stockGroup,
supplierId: throwSku.supplierId,
department: throwSku.department
});
throwSkuSchema.save(function (err) {
if (err) {
console.log(err);
} else {
importCount++;
}
});
});

#######2、循环完后再返回############
console.log(importCount);
res.jsonp(importCount);

以上是部分代码,想问下怎么用async.forEach()来让程序异步把全部数据都保存到数据库后再让res返回请求。
现在的情况是 假如我传过来的数组长度为2,还在循环的时候就打印出来了个0。

http://cnodejs.org/topic/56aad41a26d02fc6626bb369