What is the difference between concurrent.futures and asyncio.futures?

Question:

To clarify the reason for this question:

  1. It is confusing to use two modules with the same name. What do they represent that makes them distinct?

  2. What task(s) can one solve that the other can’t and vice-versa?

Asked By: sargas

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Source

Answers:

From the docs:

[asyncio provides a] Future class that mimics the one in the concurrent.futures module, but adapted for use with the event loop;

Answered By: chepner

The asyncio documentation covers the differences:

class asyncio.Future(*, loop=None)

This class is almost compatible with concurrent.futures.Future.

Differences:

  • result() and exception() do not take a timeout argument and raise an exception when the future isn’t done yet.
  • Callbacks registered with add_done_callback() are always called via the event loop’s call_soon_threadsafe().
  • This class is not compatible with the wait() and as_completed() functions in the concurrent.futures package.

This class is not thread safe.

Basically, if you’re using ThreadPoolExecutor or ProcessPoolExecutor, or want to use a Future directly for thread-based or process-based concurrency, use concurrent.futures.Future. If you’re using asyncio, use asyncio.Future.

Answered By: dano