New submission from Shankar Unni: I know that an earlier request to use nanosleep() has been rejected as "wontfix", but I'm filing this one for a different reason.
Today, timemodule.c:floatsleep() calls select() on platforms that support it. On Linux, select() with a timeout has an unfortunate property that it is very sensitive to clock jumps, because it computes a sleep end time based on the current kernel timestamp. If the system clock is yanked back (by ntpd, or other processes), then the process can end up sleeping for a very long time. (E.g. if the clock is yanked back by half an hour while we are in the middle of, say, a sleep(10), then the process will sleep until "original_kernel_clock+10", which will turn into a half-hour sleep. Yes, systems shouldn't jerk their clocks around, but we can't often control this sort of thing on end-user environments. Using clock_nanosleep(CLOCK_MONOTONIC, 0, <timespec>, NULL) makes the sleep a much more reliable thing, and mostly insensitive to such jumps. (It'll still be affected by any adjtime(), but that's OK in this case). ---------- components: Library (Lib) messages: 216799 nosy: shankarunni priority: normal severity: normal status: open title: time.sleep (floatsleep()) should use clock_nanosleep() on Linux type: behavior _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue21302> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
