March 2022
Intermediate to advanced
522 pages
13h 52m
Chinese
Content preview from Python语言及其应用（第2版）
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进程和并发
｜
257
Dryer process 44448 is done
20
秒之后，其他烘干员进程得到了
bloop
调用的返回值
None
，表明其已经超时。这些进程
输出最后的消息并退出：
Dryer process 44447 is done
Dryer process 44446 is done
等到最后一个烘干员进程退出，主程序结束。
[1]+ Done python redis_dryer2.py
15.3.9
队列之外的选择
加入的功能越多，流水线就越有可能出问题。如果需要为宴会清洗盘子，那么工人数量够
不够？如果烘干员喝多了怎么办？如果水槽堵了怎么办？真是操不完的心！
怎么解决这些麻烦事？有
3
种常用技术。
闷头干活
只管传递，不管后果，即便没人接收。这就是把盘子扔地上的方法。
请求 – 回应
对于每个盘子，洗盘工需要收到烘干员的确认，烘干员需要收到放置工人的确认。
反压或节流
如果下游人员跟不上，则指示上游人员降低速度。
在现实系统中，需要注意工人是否跟得上需求，不然就会听到盘子落地的声音。可以把新
的任务添加到一个待处理的列表中，同时一些工人进程会取出最新的消息，加入工作列
表。消息处理完毕之后，将其从工作列表中删除并添加到一个完成列表中。这可以让你知
道哪些任务失败或是耗费了太长时间。你可以自己使用
Redis
实现
，也可以使用别人已经
写好并测试过的系统。一些基于
Python
的队列包加入了这种额外的管理功能。
•
celery
可以使用本章已经讨论过的
multiprocessing
、
gevent
等方法，以同步或异步形 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.