[Python-ideas] An alternate approach to async IO

[Sturla Molden]

Den 28. nov. 2012 kl. 01:15 skrev Trent Nelson <trent at snakebite.org>:

> 
>    Right, that's why I proposed using non-Python types as buffers
>    whilst in the background IO threads.  Once the thread finishes
>    processing the event, it pushes the necessary details onto a
>    global interlocked list.  ("Details" being event type and possibly
>    a data buffer if the event was 'data received'.)
> 
>    Then, when aio.events() is called, CPython code (holding the GIL)
>    does an interlocked/atomic flush/pop_all, creates the relevant
>    Python objects for the events, and returns them in a list for
>    the calling code to iterate over.
> 
>    The rationale for all of this is that this approach should scale
>    better when heavily loaded (i.e. tens of thousands of connections
>    and/or Gb/s traffic).  When you're dealing with that sort of load
>    on a many-core machine (let's say 16+ cores), an interlocked list
>    is going to reduce latency versus 16+ threads constantly vying for
>    the GIL.
> 
>    

Sure, the GIL is a lot more expensive than a simple mutex (or an interlocked list), so avoiding a GIL-release and reacquire on each io completion event might be an advantage.

Sturla