I knew about leap seconds, but I never kept up with when they occurred. My oldest son recently called so we could celebrate his one billionth second since birth. He mentioned that in determining the appropriate second, he had to account for fifteen leap seconds since his birth. It was a fun celebration, even though it only lasted a second.<div>
<br></div><div>I have never programmed any system level applications, but I have programmed data acquisition and reporting systems many times. I never had any trouble with adjusting the time on any of them. For me, there has always been the assumption that no two clocks could be expected to show the same time. So periodically making an adjustment was natural and did not cause trouble. We have some SQL Server apps which will not respond to queries if the client's clock is more than five minutes different from the server's, but we don't let them get that far apart. <br>
<br><div class="gmail_quote">On Wed, Jul 4, 2012 at 10:39 AM, Ron Frazier (ALE) <span dir="ltr"><<a href="mailto:atllinuxenthinfo@techstarship.com" target="_blank">atllinuxenthinfo@techstarship.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi all,<br>
<br>
Around the beginning of this year, I was doing quite a bit of research into ntp and gps and eventually set up my own gps based ntp time server in both Linux and Windows. At the end of June, a leap second was inserted into the time sequences of the clocks on Earth. For those that may not know what that is, the atomic clocks are coordinated with the earth's rotation, so, for example, when the clock says noon, the sun is always roughly overhead. However, the earth's rotation speeds up and slows down at times. So,sometimes, we have to tweak the clocks to match the earth again. At the end of June, an extra second was inserted. Normally, the seconds go 58 ... 59 ... 00. This time, they went 58 ... 59 ... 60 ... 00. As it turns out, this crashed a number of servers.<br>
<br>
I find this very interesting, and somewhat scary as a potential programmer. Since I'm thinking of learning programming again, and since I have an interest in timekeeping, I have considered writing a world clock program etc., to show the time in different parts of the world. However, prior to my NTP research, I never knew about the leap second. So, there would have been a good possibility, had I written the program prior to this year, that my program would have crashed as well.<br>
<br>
So, my question is, how many of you knew about leap seconds prior to this incidence of it and prior to my describing it. If you were writing a clock program, would you have known to account for this?<br>
<br>
Sincerely,<br>
<br>
Ron<br>
<br>
<br>
--<br>
<br>
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<br>
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<br>
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<br>
Ron Frazier<br>
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