[Openmcl-devel] Improving bordeaux-threads on CCL
James M. Lawrence
llmjjmll at gmail.com
Tue Sep 10 18:05:13 CDT 2013
> Since UNWIND-PROTECT cleanup forms are effectively run with
> interrupts disabled in CCL by default,
Thanks, I wasn't aware that unwind-protect had that behavior. CCL
appears to be the only implementation that does this.
>> Interrupting threads is generally bad news because Lisp code is not
>> generally expected to be interrupt-safe.
> Huh. I'd generally say that that's more true of C code than Lisp code,
> but I'd also find it hard to make sweeping generalizations like that.
> Perhaps different people have different general expectations.
The kind of acquire-then-release/do-then-undo pattern in the original
condition-wait is pretty common, and such code is unsafe. One reason I
asked about ccl:wait-on-semaphore was
(defun %wait-on-semaphore-ptr (s seconds milliseconds &optional flag)
(if (istruct-typep flag 'semaphore-notification)
(setf (semaphore-notification.status flag) nil)
(report-bad-arg flag 'semaphore-notification)))
A thread could be terminated after setf but before without-interrupts.
That may not matter in this case, but it's the sort of thing that
prompts me to ask about interrupt-safety.
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