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From: Michael Pearce <Michael.Pearce@ig.com>
To: "dev@hawq.incubator.apache.org" <dev@hawq.incubator.apache.org>
Subject: Re: s/gettimeofday/clock_gettime/ in hawq?
Thread-Topic: s/gettimeofday/clock_gettime/ in hawq?
Thread-Index: AQHSvMYBXO7ehUUve0Kh6SLoWLVx66HUIQ6F
Date: Mon, 24 Apr 2017 07:40:41 +0000
Message-ID: <1493019734886.71870@ig.com>
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archived-at: Mon, 24 Apr 2017 07:40:53 -0000

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 OS=
X 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 gettime=
ofday 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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