关于使用协程的一点疑问 - V2EX
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aoscici2000

关于使用协程的一点疑问

  •  
  •   aoscici2000 Dec 23, 2019 4638 views
    This topic created in 2336 days ago, the information mentioned may be changed or developed.
    class ProductDetailHandler(BaseHandler): async def get(self): _id = self.get_argument('id') product = await mgo.product.find_one({'_id': ObjectId(_id)}) sku = await mgo.sku.find({'pid': _id}).to_list(None) seller = await mgo.user.find_one({'_id': product['seller_id']}) product['seller'] = seller['name'] product['sku'] = sku self.write({'err_code': 0, 'data': product}) 

    像网上找的这个例子, 有一点小疑问, 这里本身 get() 就是一个协程函数了吧? 里面再开三个的话, 它自身不就是等于没事做了吗? 这算不算一种资源浪费?

    6 replies    2019-12-23 22:44:02 +08:00
    wzwwzw
        2
    wzwwzw  
       Dec 23, 2019
    await 会把 cpu 资源让出来。
    keepeye
        3
    keepeye  
       Dec 23, 2019
    asyncio.ensure_future 可以不用 await
    CzaOrz
        4
    CzaOrz  
       Dec 23, 2019   1
    好像是 tornado~,你说的再开三个是指三次`await`,但是后面我没懂。
    三次`await`就是三次`中断`,每次中断都有注册`任务`添加到`期程`的操作。注册后会释放 CPU 资源,之后就是等待或者执行其他已完成的`任务`,所以并没有浪费资源,整个流程没有线程的切换,效率高。而任务什么时候完成,由操作系统调度通知。
    aoscici2000
        5
    aoscici2000  
    OP
       Dec 23, 2019
    @CzaOrz 大概懂了, 谢谢哈
    676529483
        6
    676529483  
       Dec 23, 2019
    单次调用肯定没区别啊,执行次数越多,优势越大
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