5 ms·

FTA: "Assuming servers are kept synchronized enough (the enough depending on your application), you may just solve the problem by acquiring time precisely enoug

by leif 12y ago

FTA: "Assuming servers are kept synchronized enough (the enough depending on your application), you may just solve the problem by acquiring time precisely enough." How on earth are "sub-microsecond timers" supposed to be synchronized anywhere?

dclusin 12y ago
We have special hardware that syncs our servers to an atomic clock in Colorado. It's about +/- microseconds off. Not sure about sub microsecond tho. Another problem with this is you will run into clock drift and NTP time adjustment bugs. Honestly I stopped reading once he mentioned that time was going to be his secret sauce. There are just too many subtle issues with using that as your globally unique identifier.
- apaprocki 12y ago
  If I'm reading the spec sheets correctly, the datacenter rubidium/gps clocks typically used advertise < 5x10^-9 (worst case) to < 5x10^-11 (best case) accuracy.
  - dclusin 12y ago
    Which spec sheet? Would like to read more about these.
    - deleted 12y ago
      [deleted]
    - apaprocki 12y ago
      Something like this: http://www.spectracomcorp.com/Desktopmodules/Bring2Mind/DMX/Download.aspx?EntryId=287&PortalId=0 http://www.spectracomcorp.com/Desktopmodules/Bring2Mind/DMX/... The units are a bit confusing but the accuracy still translates down to a handful of nanoseconds per month, I believe.
deleted 12y ago
[deleted]
profquail 12y ago
Precision Time Protocol: http://en.m.wikipedia.org/wiki/Precision_Time_Protocol http://en.m.wikipedia.org/wiki/Precision_Time_Protocol
- noselasd 12y ago
  Or a GPS disciplined clock
- leif 12y ago
  OK but the point in the article is to reduce reliance on shared state. This doesn't work in a database.
yodaiken 12y ago
This is very possible with high quality software, for example, see http://fsmlabs.com http://fsmlabs.com