Lots of concurrency
Jecel Assumpcao Jr
jecel at merlintec.com
Fri Oct 26 06:35:24 UTC 2001
On Thursday 25 October 2001 13:01, Ken Kahn wrote:
> I think her problem is that her model of programming is sequential as
> a result of her year of Logo programming. [...]
I agree 100%. There is no way that she would have come up with a time
slicing solution if she hadn't been taught to use it in these kinds of
situations. Check out the cover of the Logo issue of Byte magazine
(August 1982): it is a listing for a program where the single turtle is
time sliced to simulate four turtles.
> [3 bears definition of asynchronous]
>
> These problems with asynchronous messages don't match my experience.
> Maybe these problems are completely a consequence of mixing
> asynchrony and sequential programming.
Exactly - these happened in the context of people using C tools on the
Transputer (I used Occam or assembler instead). With synchronous
messages you get an automatic send/receive order on the client (since
sending implies waiting for a reply) and receive....send on the server
(in the case where receiving is implicit and follows automatically
after sending the reply to the previous messages).
With assynchronous messages I saw a lot of send/send or receive/receive
bugs in other people's code though it was never a problem for me. Note
that you can have the exact same problems with Occam's kind of
synchronous messages. Hmmm... perhaps I should have talked about "one
way" and "two way" messages instead?
-- Jecel
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