On 23.08.2015 23:43, Charles Hixson wrote:
If I understand correctly asyncio, coroutines, etc. (and, of course,
Threads) are not simultaneously executed, and that if one wants that
one must still use multiprocessing. But I'm not sure. The note is
still there at the start of threading, so I'm pretty sure about that one.
The requirement that coroutines always be awaited seems to confirm
this, but doesn't really say so explicitly. And the concurrent.futures
can clearly be either, depending on your choices, but the chart in
18.5.3.1.3 Example: Chain coroutines is of a kind that I am more
familiar with in the context of multiprocessing. (E.g., the only gap
in the chart, which extends across all headings is when a result is
being waited for during a sleep.) For threaded execution I would
expect there to be a gap whenever processing is shifted from one
column to another.
If someone has authority to edit the documentation a comment like:
If you want your application to make better use of the computational
resources of multi-core machines, you are advised to use
multiprocessing
<https://docs.python.org/3.5/library/multiprocessing.html#module-multiprocessing>
or concurrent.futures.ProcessPoolExecutor
<https://docs.python.org/3.5/library/concurrent.futures.html#concurrent.futures.ProcessPoolExecutor>.
However, threading is still an appropriate model if you want to run
multiple I/O-bound tasks simultaneously.
(to quote from the threading documentation) would be helpful at or
very near the top of each of the appropriate modules. It would also
be useful if the modules that were definitely intended to result in
simultaneous execution, when feasible, were so marked quite near the top.
OTOH, I may be mistaken about coroutines. I haven't been able to tell.
P.S.: I do note that the threading comment was a "*CPython
implementation detail:"*, and not a part of the Python
specifications. But CPython is, I believe, a sufficiently dominant
implementation that such details are quite important.
We already have a discussion on python-ideas where we collected many
many aspects on this particular subject.
The results so far:
https://mail.python.org/pipermail/python-ideas/2015-July/034813.html
I know the table is a bit screwed but you will be able to handle that.
Do you have anything you want to add to it?
Cheers,
Sven
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