2014-02-10 2:38 GMT+01:00 Guido van Rossum <gu...@python.org>:
>> I wrote asyncio.wait(*readlines) in my test program and Python became
>> slow and ate more and more memory. readlines is declared as
>> [proc.stdout.readline(), proc.stderr.readline()].
>
> I guess that was Trollius? Tulip's wait() has a lone * after the first
> argument so it would have raised an immediate error. (Please always state
> whether you observed something in Trollius or Tulip. They may be similar,
> but details like this are often different. As you wrote earlier, Python 3
> really is better. :-)
Oh, I missed the fact that Tulip has a different prototype. Yes, I got
the issue with Trollius which doesn't have "*" in its prototype.
I can maybe add an extra check in Trollius to avoid the trap.
>> asyncio.wait(future) calls set(future) which can enter an unlimited
>> loop (it's the case for StreamReader.readline coroutine at least...)
>> :-(
>
> Wow, that feels weird. I guess this is also only Trollius? In Tulip
> iterating over a Future gives you an exception at the second __next__()
> call.
In Tulip, I got an AssertionError("yield from wasn't used with
future"). Cool :-)
> wait() and as_completed() are low-level functions that were defined in PEP
> 3148 (concurrent.futures) as taking sets of Futures. And they return
> Futures.
Ah ok.
>> Similar trap: subprocess.Popen(args) expects a list whereas
>> EventLoop.subprocess_exec(*args) expects multiple paramters.
>> EventLoop.subprocess_exec() should maybe also raise an error if the
>> first argument is a iterable (but not bytes or str).
>
> For those it would be a good idea to add strict type checking. (But note
> that there are no Futures involved.)
>
> For wait() and as_completed(), I suppose you could add an explicit
>
> assert not isinstance(fs, futures.Future) and not iscoroutine(fs)
>
> at the top (or raise an explicit TypeError).
Ok, I will open an issue with a patch for these checks.
Thanks for the explanation.
Trollius and Tulip are very close, and sometimes very different :-)
Especially when it's related to internals like Task._step().
So why people still use Python 2? :-)
Victor
