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From Paul Guo <paul...@gmail.com>
Subject Re: s/gettimeofday/clock_gettime/ in hawq?
Date Tue, 25 Apr 2017 02:16:39 GMT
Thanks. So we could check whether clock_gettime() exists or not during
configure and then in code if needed we fall back to gettimeofday().

2017-04-24 15:40 GMT+08:00 Michael Pearce <Michael.Pearce@ig.com>:

> Hi,
>
> clock_gettime i believe was made native available in macOS Sierra (10.12).
>
> prior versions though don't afaik. Though with the aggressive upgrade of
> OSX on apple devices that apple push, to end users is this really a concern?
>
> As per posix guidance also, what you suggest is also recommended as
> gettimeofday is obsolescent.
>
> http://pubs.opengroup.org/onlinepubs/9699919799/
> functions/gettimeofday.html
>
> Regards
> Mike
>
> ________________________________________
> From: Paul Guo <paulguo@gmail.com>
> Sent: Monday, April 24, 2017 6:36 AM
> To: dev@hawq.incubator.apache.org
> Subject: s/gettimeofday/clock_gettime/ in hawq?
>
> Hi,
>
> HAWQ sometimes use gettimeofday() syscall for some timeout check in various
> module, however it could be affected by ntp, so the timeout checking logic
> could be wrong sometimes. I would propose to use clock_gettime() to replace
> it on Linux (I have not investigated the alternative on other platforms
> e.g. mac). Both gettimeofday() and clock_gettime() are fast vdso sys call
> so I do not expect there is performance loss in some case where there are
> frequent calls of gettimeofday(). By the way, I found some gettimeofday()
> calls on postgresql and gpdb, so they might have this issue also.
>
> Regards,
>
> Paul
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