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* [Bug c++/58931] New: condition_variable::wait_until overflowed by large time_point<steady_clock>
@ 2013-10-30 22:46 lundberj at gmail dot com
2013-10-31 13:29 ` [Bug c++/58931] " redi at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: lundberj at gmail dot com @ 2013-10-30 22:46 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58931
Bug ID: 58931
Summary: condition_variable::wait_until overflowed by large
time_point<steady_clock>
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lundberj at gmail dot com
With valid but large steady clock time_points, condition_variable.wait_until
does not sleep at all, but instead continues as if the time was passed.
Perhaps related to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54562
Example:
#include <chrono>
#include <mutex>
#include <condition_variable>
int main(){
std::mutex m;
std::condition_variable cv;
std::unique_lock<std::mutex> lk(m);
// does not sleep at all:
cv.wait_until(lk,
std::chrono::time_point<std::chrono::steady_clock>::max());
// sleeps fine:
//cv.wait_until(lk,
// std::chrono::steady_clock::now()+10000*std::chrono::hours{24*365});
}
cheers / Johan -thanks for a great compiler!
PS.
* I compiled gcc with --enable-libstdcxx-time=yes. Using 64 bit linux 3.5.0
* The bug does not occur with system_clock.
* I used time_point max() to let a worker thread wait when a queue of delayed
events was empty.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/58931] condition_variable::wait_until overflowed by large time_point<steady_clock>
2013-10-30 22:46 [Bug c++/58931] New: condition_variable::wait_until overflowed by large time_point<steady_clock> lundberj at gmail dot com
@ 2013-10-31 13:29 ` redi at gcc dot gnu.org
2013-11-11 12:55 ` [Bug libstdc++/58931] " redi at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: redi at gcc dot gnu.org @ 2013-10-31 13:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58931
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |redi at gcc dot gnu.org
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I have a fix for PR 54562 so I'll see if it solves this.
N.B. --enable-libstdcxx-time=yes should not be necessary for 4.8 if you have
glibc 2.17 or later.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug libstdc++/58931] condition_variable::wait_until overflowed by large time_point<steady_clock>
2013-10-30 22:46 [Bug c++/58931] New: condition_variable::wait_until overflowed by large time_point<steady_clock> lundberj at gmail dot com
2013-10-31 13:29 ` [Bug c++/58931] " redi at gcc dot gnu.org
@ 2013-11-11 12:55 ` redi at gcc dot gnu.org
2015-05-09 22:45 ` aaron at aarongraham dot com
2020-10-03 17:55 ` mac at mcrowe dot com
3 siblings, 0 replies; 5+ messages in thread
From: redi at gcc dot gnu.org @ 2013-11-11 12:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58931
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2013-11-11
Component|c++ |libstdc++
Ever confirmed|0 |1
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixing PR 54562 doesn't help. This can be reduced to
#include <chrono>
#include <cassert>
int main()
{
using StClock = std::chrono::steady_clock;
using SysClock = std::chrono::system_clock;
auto st_atime = std::chrono::time_point<StClock>::max();
const StClock::time_point st_now = StClock::now();
const SysClock::time_point sys_now = SysClock::now();
const auto delta = st_atime - st_now;
const auto sys_atime = sys_now + delta;
assert( sys_atime > sys_now );
}
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug libstdc++/58931] condition_variable::wait_until overflowed by large time_point<steady_clock>
2013-10-30 22:46 [Bug c++/58931] New: condition_variable::wait_until overflowed by large time_point<steady_clock> lundberj at gmail dot com
2013-10-31 13:29 ` [Bug c++/58931] " redi at gcc dot gnu.org
2013-11-11 12:55 ` [Bug libstdc++/58931] " redi at gcc dot gnu.org
@ 2015-05-09 22:45 ` aaron at aarongraham dot com
2020-10-03 17:55 ` mac at mcrowe dot com
3 siblings, 0 replies; 5+ messages in thread
From: aaron at aarongraham dot com @ 2015-05-09 22:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58931
--- Comment #4 from Aaron Graham <aaron at aarongraham dot com> ---
See bug 41861 for discussion of steady_clock wrt condition_variable.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug libstdc++/58931] condition_variable::wait_until overflowed by large time_point<steady_clock>
2013-10-30 22:46 [Bug c++/58931] New: condition_variable::wait_until overflowed by large time_point<steady_clock> lundberj at gmail dot com
` (2 preceding siblings ...)
2015-05-09 22:45 ` aaron at aarongraham dot com
@ 2020-10-03 17:55 ` mac at mcrowe dot com
3 siblings, 0 replies; 5+ messages in thread
From: mac at mcrowe dot com @ 2020-10-03 17:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58931
Mike Crowe <mac at mcrowe dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mac at mcrowe dot com
--- Comment #6 from Mike Crowe <mac at mcrowe dot com> ---
This problem isn't as serious now that waiting on std::chrono::steady_clock
doesn't use the generic wait_until implemenation, but it's worth fixing
regardless.
I have a reproduction case and Aaron's fix in attachment 43261 (with some minor
tweaks to accommodate the recent addition of __detail::ceil) still appears to
work.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2013-10-30 22:46 [Bug c++/58931] New: condition_variable::wait_until overflowed by large time_point<steady_clock> lundberj at gmail dot com
2013-10-31 13:29 ` [Bug c++/58931] " redi at gcc dot gnu.org
2013-11-11 12:55 ` [Bug libstdc++/58931] " redi at gcc dot gnu.org
2015-05-09 22:45 ` aaron at aarongraham dot com
2020-10-03 17:55 ` mac at mcrowe dot com
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