[Python-ideas] micro-threading PEP proposal (long) -- take 2!

[Andrew Akira Toulouse]

Forgive the pedantry: do you mean "breathe", rather than "breath"?

On Wed, Aug 27, 2008 at 6:42 PM, Bruce Frederiksen <dangyogi at gmail.com>wrote:

> In this case, you're misunderstanding :-).
>
> What I meant by a "long running" micro_thread starving other micro-threads,
> was a micro_thread that doesn't do anything that would cause it to be
> suspended (e.g., I/O, sleep).
>
> For example, calculating the number PI to 2000 digits will starve other
> micro_threads.
>
> Each time a micro_thread does something which causes it to be suspended
> (like a file.read that needs to access the disk, a socket.recv or a
> time.sleep), other micro_threads may run.  So the first micro_thread doesn't
> cause the whole os-thread (generally the whole Python program) to be
> suspended, like it does now.
>
> But if one micro_thread uses the CPU for a long time without doing any I/O,
> then other micro_threads are starved because micro_threads are
> non-preemptive (unlike os-threads).
>
> I'm adding a "breath" function that allows responsible micro_threads to
> "come up for air" periodically, to give other micro_threads a chance to run.
>  But nothing forces a micro_thread to cooperate like this...
>
> I hopes this helps to clear things up!
>
> -bruce
>
>
>
> Jerry Spicklemire wrote:
>
>> Bruce wrote:
>>
>> "The micro_pipes use the C_deferreds to suspend the thread
>> and allow other threads to run."
>>
>> http://mail.python.org/pipermail/python-ideas/2008-August/001848.html
>>
>>
>> However, in the PEP you mention, among the short list of
>> disadvantages:
>>
>> "since there is no preemption, a long running micro-thread will starve
>> other micro-threads"
>>
>> http://mail.python.org/pipermail/python-ideas/2008-August/001825.html
>>
>>
>>
>> Are these two point contradictory, or am I simply misunderstanding, as
>> usual.
>>
>>
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