I'm really surprised by the servers being within 500ms of each other, to be honest.
I've got a timesheet product on GAE and I've had clock skew of more than a minute between some instances, although it's fairly rare that it's anywhere near that large and it's a lot better now than it ever has been. Cheers, Simon On Saturday, 30 June 2012 01:04:47 UTC+1, Cesium wrote: > > Hey Jeff, > > Think of, for example, a global network of sensors measuring geo-physical > phenomena. > They need to be synchronized. The maximum uncertainly is determined by the > phenomenon being measured. > > It all boiled down to needing a time server on port 80 whose difference > from UTC was less than > about 500ms. > > I really didn't want to use the usual port 13 servers. So I wrote a GAE > time server. > > Three years have past since I last looked at this > issue.<https://groups.google.com/forum/?fromgroups#!topic/google-appengine/wNFhGaIUlXQ> > > All the data I have collected show that GAE's server's are well within > 500ms of UTC(NIST). > Even without 'guarantees.' That's good enough for me. > > But today I learn that App Engine has a cool, clever workaround that > slowly slews it 1 second off UTC(NIST). > > It's not the length of the individual seconds (frequency) that counts. > It's the integral of all these seconds (phase) that matters. > That integral in this case will be an error of 1 second. Next time the ERS > demands a leap second, the error will be 2 seconds. > This leads to a time stamp that no longer accurately reflects statements > like: "Number of seconds since 1 Jan 1970 00:00:00 UTC." > > I'm just heart-broken to hear that Google decided to brush these leap > seconds under the rug by changing the rate of their time-scale. > They are real points on the UTC time-scale, and important things happen on > our planet during these leap seconds. > > The punchline is that I did some poking around and found a buddy that > serves UTC(NIST) on port 80. > > Sweet! > > David > > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/Z70_fuQQ_RQJ. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
