[Haskell-cafe] Re: Python's big challenges, Haskell's big advantages?

Jonathan Cast jonathanccast at fastmail.fm
Wed Sep 17 15:03:21 EDT 2008

On Wed, 2008-09-17 at 18:40 +0000, Aaron Denney wrote:
> On 2008-09-17, Arnar Birgisson <arnarbi at gmail.com> wrote:
> > Hi Manlio and others,
> >
> > On Wed, Sep 17, 2008 at 14:58, Manlio Perillo <manlio_perillo at libero.it> wrote:
> >>> http://www.heise-online.co.uk/open/Shuttleworth-Python-needs-to-focus-on-future--/news/111534
> >>>
> >>> "cloud computing, transactional memory and future multicore processors"
> >>>
> >>
> >> Multicore support is already "supported" in Python, if you use
> >> multiprocessing, instead of multithreading.
> >
> > Well, I'm a huge Python fan myself, but multiprocessing is not really
> > a solution as much as it is a workaround. Python as a language has no
> > problem with multithreading and multicore support and has all
> > primitives to do conventional shared-state parallelism. However, the
> > most popular /implementation/ of Python sacrifies this for
> > performance, it has nothing to do with the language itself.
> Huh.  I see multi-threading as a workaround for expensive processes,
> which can explicitly use shared memory when that makes sense.

That breaks down when you want 1000s of threads.  I'm not aware of any
program, on any system, that spawns a new process on each event it wants
to handle concurrently; systems that don't use an existing user-space
thread library (such as Concurrent Haskell or libthread [1]) emulate
user-space threads by keeping a pool of processors and re-using them
(e.g., IIUC Apache does this).

Any counter-examples?


[1] http://swtch.com/plan9port/man/man3/thread.html

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