GNU bug report logs -
#19581
'sleep' return value is incorrectly rounded
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(Tue, 13 Jan 2015 12:59:02 GMT)
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ludo <at> gnu.org (Ludovic Courtès)
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(Tue, 13 Jan 2015 12:59:02 GMT)
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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):
I just noticed that ‘sleep’ essentially always rounds down its return
value, which makes it unreliable, as in this example:
--8<---------------cut here---------------start------------->8---
$ time guile -c '(sigaction SIGINT +) (call-with-new-thread (lambda () (let loop () (kill (getpid) SIGINT) (loop)))) (let loop ((n 3)) (when (> n 0) (loop (sleep (pk "s" n)))))'
;;; ("s" 3)
;;; ("s" 2)
;;; ("s" 1)
real 0m0.039s
user 0m0.052s
sys 0m0.017s
--8<---------------cut here---------------end--------------->8---
Here ‘loop’ is meant to assure we sleep for roughly 3 seconds, but
because of the incorrect rounding, we end up not sleeping at all.
Ludo’.
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(Thu, 23 Jun 2016 09:03:02 GMT)
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Message #8 received at 19581 <at> debbugs.gnu.org (full text, mbox):
Hi :)
On Tue 13 Jan 2015 13:58, ludo <at> gnu.org (Ludovic Courtès) writes:
> I just noticed that ‘sleep’ essentially always rounds down its return
> value, which makes it unreliable, as in this example:
>
> $ time guile -c '(sigaction SIGINT +) (call-with-new-thread (lambda () (let loop () (kill (getpid) SIGINT) (loop)))) (let loop ((n 3)) (when (> n 0) (loop (sleep (pk "s" n)))))'
>
> ;;; ("s" 3)
>
> ;;; ("s" 2)
>
> ;;; ("s" 1)
>
> real 0m0.039s
> user 0m0.052s
> sys 0m0.017s
>
> Here ‘loop’ is meant to assure we sleep for roughly 3 seconds, but
> because of the incorrect rounding, we end up not sleeping at all.
Hummmmmmmmmm.
I don't think we can change anything in 2.0. Right?
In master, how about (1) we allow sleep to take any real number, in
seconds; (2) sleep returns an inexact real number. Then we can
deprecate usleep and "standardize" on sleeping in units of seconds.
Internally we refactor scm_std_usleep/* to take a 64-bit double for the
number of seconds to sleep and return a double for the time remaining.
WDYT?
Andy
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(Thu, 23 Jun 2016 13:10:01 GMT)
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Message #11 received at 19581 <at> debbugs.gnu.org (full text, mbox):
Hello,
Andy Wingo <wingo <at> pobox.com> skribis:
> On Tue 13 Jan 2015 13:58, ludo <at> gnu.org (Ludovic Courtès) writes:
>
>> I just noticed that ‘sleep’ essentially always rounds down its return
>> value, which makes it unreliable, as in this example:
>>
>> $ time guile -c '(sigaction SIGINT +) (call-with-new-thread (lambda () (let loop () (kill (getpid) SIGINT) (loop)))) (let loop ((n 3)) (when (> n 0) (loop (sleep (pk "s" n)))))'
>>
>> ;;; ("s" 3)
>>
>> ;;; ("s" 2)
>>
>> ;;; ("s" 1)
>>
>> real 0m0.039s
>> user 0m0.052s
>> sys 0m0.017s
>>
>> Here ‘loop’ is meant to assure we sleep for roughly 3 seconds, but
>> because of the incorrect rounding, we end up not sleeping at all.
>
> Hummmmmmmmmm.
>
> I don't think we can change anything in 2.0. Right?
>
> In master, how about (1) we allow sleep to take any real number, in
> seconds; (2) sleep returns an inexact real number. Then we can
> deprecate usleep and "standardize" on sleeping in units of seconds.
> Internally we refactor scm_std_usleep/* to take a 64-bit double for the
> number of seconds to sleep and return a double for the time remaining.
Sounds like a plan. There could be programs that will break if ‘sleep’
gives them an inexact instead of an integer. Maybe we can assume this
is an unlikely situation, though.
Thoughts?
Ludo’.
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(Mon, 27 Jun 2016 08:11:01 GMT)
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Message #14 received at 19581 <at> debbugs.gnu.org (full text, mbox):
On Sun 26 Jun 2016 23:37, Arne Babenhauserheide <arne_bab <at> web.de> writes:
> ping?
Let's follow up on bug #19581.
Thanks,
Andy
This bug report was last modified 7 years and 298 days ago.
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