[Python-Dev] Re: Signal-resistant code (was: Two random and nearly unrelated ideas)

Guido van Rossum guido@python.org
Wed, 04 Sep 2002 09:25:01 -0400

> > Signals: just say no.  It is impossible to write correct code in the
> > presence of signals.
> Wrapping all I/O calls with PyOS_ wrappers would be a good start.

And what should those wrappers do?

> After that the wrappers can be modified to retry the call on EINTR.

But that's not always what you want to happen!  E.g. if an app is
blocked on a read and uses an alarm to bail out of the read.

> This should solve all the problems I have encountered with
> interference to Python code by signals. Any other problems I should
> be aware of?

There's no way to sufficiently test a program that uses signals.  The
signal handler cannot touch *any* data, which makes it pretty useless.

--Guido van Rossum (home page: http://www.python.org/~guido/)