[Openmcl-devel] async signals
mega at hotpop.com
Thu Sep 1 07:52:11 UTC 2005
Please think of this as a cross-fertilization attempt between
implementations :-), although I hope SBCL stands to gain more from your
understanding of the subject.
Providing sane semantics for portable code is not easy when async
signals are involved especially for unwind-protect. The problems are
Some thoughts and a possible, but quite down to earth,
let's-work-around-most-of-it strategy is here:
Since then I've realized that most signal handlers (sigprof,
sigchld, ...) can be reasonably expected not to unwind the stack beyond
the handler itself, almost as if they had a separate thread. This kind
of safety can be optionally enforced by the implementation on a
That leaves C-c (that brings up the debugger), with-timeout and
terminate-thread all of which are implemented by interrupt-thread that
plays the part of openmcl's process-interrupt. Oh, and cleanly shutting
down a thread/process seems problematic for the same reasons.
I've read that openmcl checks for pending interrupts at safe-points.
Where are these safe points? Do they help with issues above?
Thanks, Gábor Melis
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