If the servers are synced via NTP, they should generally be accurate to within a few dozen ms. However, I've seen machines using NTP be off by a few seconds, or even minutes on occasion. I know Googlers have mentioned encountering servers that are out-of-sync, significantly in some cases.
Calvin, does Google serve robots.txt off of one machine? Otherwise it seems like you might be making a request to another cluster with the same problem to 'adjust' your times. Dan, are you trying to order all of those requests or subsets? Are you sustaining those rates or do they occur in bursts? You're going to have another issue too. Incoming requests will occasionally fail or be delayed so later requests might hit a server before an earlier request. Is the source of the data user-requests or is something generating the data? Robert On Sun, Feb 20, 2011 at 14:37, Calvin <[email protected]> wrote: > I was just experimenting with a way to get multiple servers synchronized to > within a second. Here's what I came up with: > https://gist.github.com/836228 > > It grabs the date header off of a fetch request and calculates the delta > between the server's time and the "canonical" time. Then when you call > synchronize(date) it subtracts that delta from the supplied datetime. > The date header doesn't return microseconds, and you have to consider that > the round-trip time adds inaccuracy, so I think +/- 1 second is the best > that can be done. In my brief tests I was seeing that the app engine time > was basically the same as canonical time without doing any of this hackery. > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > 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. > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. 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.
