[Cython] cython.parallel tasks, single, master, critical, barriers

[mark florisson]

On 9 October 2011 19:54, Jon Olav Vik <jonovik at gmail.com> wrote:
> On Sun, Oct 9, 2011 at 2:57 PM, Dag Sverre Seljebotn
> <d.s.seljebotn at astro.uio.no> wrote:
>>>> with parallel.single():
>>>> same as master, except any thread may do the execution
>>>>
>>>> An optional keyword argument 'nowait' specifies whether there will be a
>>>> barrier at the end. The default is to wait.
>>
>> I like
>>
>> if parallel.is_master():
>>    ...
>> explicit_barrier_somehow() # see below
>>
>> better as a Pythonization. One could easily support is_master to be used in
>> other contexts as well, simply by assigning a status flag in the master
>> block.
>>
>> Using an if-test flows much better with Python I feel, but that naturally
>> lead to making the barrier explicit. But I like the barrier always being
>> explicit, rather than having it as a predicate on all the different
>> constructs like in OpenMP....
>
> Personally, I think I'd prefer find context managers as a very
> readable way to deal with parallelism, similar to the "threading"
> module:
>
> http://docs.python.org/library/threading.html#using-locks-conditions-and-semaphores-in-the-with-statement
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Yeah it makes a lot of sense for mutual exclusion, but 'master' really
means "only the master thread executes this peace of code, even though
other threads encounter the same code", which is more akin to 'if'
than 'with'.