Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Amazon Time Sync Service

aws.amazon.com

Post reply on HN
Print view View original

1–10 of 94 posts

Re: Amazon Time Sync Service

#3

Post by adamfeldman »

Google and GCP offer their own NTP endpoints. Does anyone know if GCP also exposes the TrueTime API to customers, or if it's only internal to Spanner?

I can't find any instance of the word "bound" in the GCP or Google NTP docs.

[1]: https://developers.google.com/time/guides#google_compute_eng...

[2]: https://cloud.google.com/compute/docs/instances/managing-ins...

Re: Amazon Time Sync Service

#4

Post by jeffbee »

One of the key aspects of the TrueTime system is any device with serious clock error is simply murdered. It seems like offering that would significantly benefit users of this AWS API.

Re: Amazon Time Sync Service

#5

Post by tyingq »

I'm curious about the title on this submission. I thought TrueTime had unusually strong guarantees about accuracy that don't seem to be called out in what I'm reading on the linked article.

Re: Amazon Time Sync Service

#6

Post by londons_explore »

It's really hard to use these API's correctly.

Remember... your CPU can halt at any time for any number of milliseconds. That means simple things like:

    upperBound, lowerBound = readTime()
    if (upperBound
Are incorrect... There is no guarantee that the 'if' statement didn't take many milliseconds, and that the stuff didn't end up happening after the deadline.

It's also very easy to write code that works, but is theoretically wrong. You will leave a hidden bug that may only rear its head years down the line.

Re: Amazon Time Sync Service

#7

Post by londons_explore »

adamfeldman wrote: post #3

Google and GCP offer their own NTP endpoints. Does anyone know if GCP also exposes the TrueTime API to customers, or if it's only internal to Spanner? I can't find any instance of the word "bound" in the GCP or Google NTP docs. [1]: https://developers.google.com/time/guides#google_compute_eng... [2]: https://cloud.google.com/compute/docs/instances/managing-ins...

I'm pretty sure if you use the GCP dataflow stuff, the dataflow worker VM's will be given access to an RPC server which has the necessary endpoints for TrueTime.

Obviously it's all a matter of reverse engineering rather than documented API's.

Re: Amazon Time Sync Service

#8

Post by sizediterable »

tyingq wrote: post #5

I'm curious about the title on this submission. I thought TrueTime had unusually strong guarantees about accuracy that don't seem to be called out in what I'm reading on the linked article.

Sorry if it's a bit sensationalized. I wanted to give some color as to why this release might be interesting and took this tweet I saw at face value https://twitter.com/rbranson/status/1455923426359578631

Re: Amazon Time Sync Service

#9

Post by drewda »

Perhaps the biggest "fake-out" in 21st century computing: Google publicly released its MapReduce paper -- directing most of the rest of the industry toward loosely coupled, overly complex distributed data processing systems like Hadoop for the following decade -- but internally they just bought a bunch of atomic clocks and built a distributed RDBMS.

I know this is a somewhat simplified story, but it does make me chuckle.

Re: Amazon Time Sync Service

#10

Post by karmakaze »

londons_explore wrote: post #6

It's really hard to use these API's correctly. Remember... your CPU can halt at any time for any number of milliseconds. That means simple things like: upperBound, lowerBound = readTime() if (upperBound Are incorrect... There is no guarantee that the 'if' statement didn't take many milliseconds, and that the stuff didn't end up happening after the deadline. It's also very easy to write code that works, but is theoret…

Is that really the API? I'm sure I'd be writing:

  lowerBound, upperBound = readTime()
often without noticing my error.
Post reply on HN