fakeaddress at nowhere.org
Fri Sep 22 15:15:35 CEST 2006
Calvin Spealman wrote:
> I repeat this all the time, but the best advice I can give you about
> using threads is to not use threads at all.
Might as well get with the times and ignore that advice.
> I would point you to good
> references like Threads Considered Harmful
Note that it's "poster boy" for multiple processes
now uses multiple threads.
> and The Problem
> with Threads
> - With Link to PDF).
The author's alternatives to threads are not available
in Python. Many Pythoners do similar things with threads,
such as use the message-passing style via the queue module.
> It might seem an inappropriate response to your
> question to simply tell you that you should not do what you are asking
> how to do, but its just the case that most often anyone without
> exposure to threads has little or no understanding on just how bad
> they are for many of the tasks they will be used for. Threads are
> difficult to control, impossible to predict, and simply one of the
> most over used, least understood causes of buggy, unmaintainable
> software in the whole spectrum of development techniques.
Threads require some study and understanding, but they work
great once one learns to use them.
> As alternatives, look into what tasks can spawn into other processes,
Unfortunately one cannot share Python objects between processes.
POSH may change that, but it looks to be stuck in alpha.
> asyncronous programming (a'la Twisted -
I find asynchronous programming much harder to manage than
threads, except for fairly simple applications where neither
one is hard.
> and co-routine and similar facilities,
> such as the tasklets of Stackless and two-way generators now included
> with Python.
Those fail at simple things such as having two of them each
waiting at a blocking call.
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