>From the gist:
- the difference between the time on AppEngine's proxy servers (as detected
in the response headers) and "local time" on AppEngine's serving machines.
local_now = datetime.utcnow()
> google_time = urlfetch.fetch('http://www.google.com/robots.txt',
> method=urlfetch.HEAD)
> google_now = datetime.strptime(google_time.headers['date'], '%a, %d %b %Y
> %H:%M:%S GMT')
> swatch_delta = local_now - google_now
This works if the proxy servers don't also have greatly varying clock-skew,
else the delta can swing in wildly unexpected ways.
saidimu
On Fri, Mar 4, 2011 at 2:13 PM, Ikai Lan (Google) <ika...@google.com> wrote:
> I'm trying to think of a solution that doesn't involve fetching data from a
> third party time service, but I'm drawing a blank. How did you detect the
> time skew in the first place?
>
> Ikai Lan
> Developer Programs Engineer, Google App Engine
> Blog: http://googleappengine.blogspot.com
> Twitter: http://twitter.com/app_engine
> Reddit: http://www.reddit.com/r/appengine
>
>
>
> On Thu, Mar 3, 2011 at 4:57 PM, Eric Ka Ka Ng <ngk...@gmail.com> wrote:
>
>> Hi Gopal, Calvin, and Ikai,
>>
>> thx all for your sharing. Calvin, your handy script implements Gopal idea
>> could be very useful to many of us ;)
>>
>> Ikai, yes, later we could do more testing and sampling, and with Calvin's
>> script, to log the time (and delta with google time) however, this is not a
>> problem frequently happen and we are currently busying with some other
>> application dev tasks, guess it may take some time to log and analyze this
>> problem, and would keep you posted. just thinking what kinds of 'examples'
>> we could provide? (you want log? data in DS? script to produce the log /
>> data? )
>>
>>
>> btw, how could we explain Brett's data pipelines' talk at 35:50 or i
>> interpret wrongly? and i believe Gopal, Calvin faced time sync issues and
>> thus have the idea and implementation to solve this (just me recently aware
>> about this problem). how much time is off did you experience?
>>
>> thx a lot!
>>
>> - eric
>>
>> On 4 March 2011 03:12, Ikai Lan (Google) <ika...@google.com> wrote:
>>
>>> Can you provide examples where the time is off by 30 minutes? This seems
>>> incorrect.
>>>
>>> There's definitely clock skew, but we're talking milliseconds, seconds or
>>> at worst, worst, worst maybe a minute or two.
>>>
>>> Ikai Lan
>>> Developer Programs Engineer, Google App Engine
>>> Blog: http://googleappengine.blogspot.com
>>> Twitter: http://twitter.com/app_engine
>>> Reddit: http://www.reddit.com/r/appengine
>>>
>>>
>>>
>>> On Thu, Mar 3, 2011 at 5:54 AM, Ng Ka Ka Eric <ngk...@gmail.com> wrote:
>>>
>>>> Hi Raymond,
>>>>
>>>> Just watched the video. Thx for pointing this reference.
>>>>
>>>>
>>>> I really didnt expect that the machines are not time synced (can be off
>>>> for 40mins?!) are there any technical difficulties to sync them? And in
>>>> this
>>>> case, for whatever reason if we want to record the time when the request is
>>>> made into DS, how can we do that?
>>>>
>>>> - eric
>>>>
>>>> Sent from my iPhone
>>>>
>>>> On 2011年3月3日, at 下午6:20, "Raymond C." <windz...@gmail.com> wrote:
>>>>
>>>> According to Brett's data pipelines' talk (
>>>> http://www.youtube.com/watch?v=zSDC_TU7rtc, around 35:50), its not
>>>>
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