Re: $SECONDS and timeout values use realtime `gettimeofday()`

[Mike Jonkmans]

On Wed, Mar 29, 2023 at 10:49:00AM -0400, Chet Ramey wrote:
> On 3/24/23 6:19 PM, William Kennington wrote:
> > Not worried, it is legitimately a problem for us to the point we are
> > currently patching bash to use the monotonic clock for seconds. It times
> > out stuff in our boot process which executes normally after the time
> > sync has completed and jumped the clock forward. Rght now, we are just
> > patching bash until we can fix all of our uses of $SECONDS. I don't
> > really have a preference for how this gets exposed (updating SECONDS to
> > use the monotonic timer, adding a new variable like MONOSECONDS, or some
> > other call to get monotonic time via clock_gettime).
> 
> Interesting. I was wondering how you got onto this, so I looked around for
> any utilities (e.g., timeout, sleep), library functions, or system calls
> that use the monotonic clock and couldn't find any. It must be too `new';
> everyone seems to use the realtime clock.
> 
> I'll take it as a feature request.

My earlier post, in help-bash:
https://lists.gnu.org/archive/html/help-bash/2020-06/msg00031.html
refers to a website pointing out problems with gettimeofday.

That website was (presumably) written in 2010/09 :
https://blog.habets.se/2010/09/gettimeofday-should-never-be-used-to-measure-time.html

So it is not that new.

It is another special case in code, which may explain the slow uptake in tools,
many of which need to be portable.

-- 
Regards, Mike Jonkmans