On 2014-08-12 18:02, cool-RR wrote:
Hello everybody! I have a question.I have a Django app running on Heroku. I need to run about 100 worker threads there to do uploads/downloads simultaneously. A Heroku Dyno has only 512MB of memory, so I'm reluctant to run 100 worker threads. (I've had Dynos crash from lack of memory when using 6 threads before.) I heard that the asyncio module is mature and ready for usage, and I was happy because I kept hearing about it in the last year, and I saw Guido's lecture about it. If I understand correctly it would let me run multiple uploads and downloads efficiently in one thread, which would conserve more resources than using threads. (Please correct me if I'm wrong.) Now, I am a little clueless about the whole way it's built, using coroutines and tricky usage of `yield from`. I figured that since this is eventually a library for concurrency, i.e. doing many tasks at the same time, there will be an API in a style of "Here are 100 tasks for you to do concurrently, let me know when they're done." I looked at the asyncio documentation page and saw that it does mention futures and executors, which is my favorite interface for doing concurrency. I was happy and I skimmed the docs. But, I couldn't find a simple way to use these. I don't want to learn how to define coroutines and use `yield from` to switch between them. (I use `yield from` regularly and fully understand how it works, I just don't write my programs that way.) What I'm expecting is something like this: download_file = lambda url: requests.get(url).content urls = ['http://google.com/file1.jpg', 'http://google.com/file2.jpg', 'http://google.com/file3.jpg'] # etc. with AsyncIOExecutor() as asyncio_executor: files = asyncio_executor.map(download_file, urls) And that's it, no coroutines, no `yield from`. Since, if I understand correctly, asyncio requires a mainloop, it would make sense for the AsyncIOExecutor to have a thread of its own in which it could run its mainloop. Is this possible? Did someone implement this?
Do you really need to upload/download that many at the same time? I'd put them into a queue and have only a few of uploading/downloading at any time. -- https://mail.python.org/mailman/listinfo/python-list
