[Pharo-project] System time

Mariano Martinez Peck marianopeck at gmail.com
Mon May 2 09:49:33 CEST 2011


On Mon, May 2, 2011 at 12:56 AM, Andres Valloud <
avalloud at smalltalk.comcastbiz.net> wrote:

> Does the Windows VM depend on QueryPerformanceCounter()?


I have no idea what that is, but a quick

grep -n "QueryPerformanceCounte" -r
~/Pharo/vm/git/cogVMMaster/blessed/platforms

tell me that not.


>
>
> On 5/1/11 16:53 , Alexandre Bergel wrote:
>
>> Strange. I cannot produce this problem on OSX.
>>
>> Alexandre
>>
>>
>> On 30 Apr 2011, at 22:15, Jimmie Houchin wrote:
>>
>>  Hello,
>>>
>>> My OS for this application is Windows. On a freshly opened image, the
>>> image and OS time are in sync. Over a period of time the image drifted 34
>>> seconds away from OS time. I do not know how long I had this image open, but
>>> it has been a number of days, possibly a week plus.
>>>
>>> I saved the image and quit. I reopened the image and did DateAndTime now
>>> and it was in sync with the OS once again. Same image, vm and OS that was
>>> out of sync by 34 seconds only one minute before.
>>>
>>> I have opened an image on my server which is also running the latest cog
>>> vm, the current Pharo 1.3 and Windows Vista. I am going to periodically do a
>>> DateAndTime now to log the drift if any. Prior to opening this image I
>>> updated the OS system clock with time.nist.gov which is about 1000 miles
>>> away.
>>>
>>> I know that within a second or so it can be subject to my coordination of
>>> doing DateAndTime now while watching my OS system clocks seconds. But 34
>>> seconds is beyond any subjective standards.
>>>
>>> The only reason I discovered this was while exploring how I want to
>>> retrieve my data, act upon my data and then pause (Delay wait) until time to
>>> repeat.
>>>    dtnow := DateAndTime now.
>>>    dtnext := DateAndTime year: 2011 month: 4 day: 30 hour: 11 minute: i
>>> second: 5.   "The next minute in the future"
>>>    (Delay forDuration: (dtnext - dtnow)) wait.
>>>
>>> I got an error, that Duration cannot be a negative number. As I processed
>>> the debugger, I saw that dtnow was greater than dtnext. I watched the OS
>>> clock and manually selected the next minute before I executed. However, I
>>> was within that 34 second window.
>>>
>>> So now I am exploring the problem.
>>>
>>> Thanks.
>>>
>>> Jimmie
>>>
>>> On 4/30/2011 5:06 PM, Alexandre Bergel wrote:
>>>
>>>> 'Time now' gives me the same result than OSX
>>>>
>>>> Alexandre
>>>>
>>>>
>>>> On 30 Apr 2011, at 16:15, Jimmie Houchin wrote:
>>>>
>>>>  On 4/30/2011 11:50 AM, Stéphane Ducasse wrote:
>>>>>
>>>>>> I am developing a time sensitive application. I poll a server every
>>>>>>> minute for new data. The data is time sensitive and the sooner I can get the
>>>>>>> data to the release of the data the better.
>>>>>>>
>>>>>>> I have noticed that Pharo's system time drifts away from the OS
>>>>>>> system time. I would really like the Pharo system time to be the correct
>>>>>>> time.
>>>>>>>
>>>>>> do you have a repeatable scenario?
>>>>>> VM
>>>>>> Image information.
>>>>>>
>>>>> Pharo 1.3 and the latest Cog.
>>>>>
>>>>>  I have not been able to find where in Pharo I can call to update the
>>>>>>> System clock to the correct time.
>>>>>>>
>>>>>> you can use OSProcess (only mac and linux)
>>>>>>
>>>>> No, that's not the problem. The OS clock is right. It's Pharo that has
>>>>> drifted away from correct time. Regardless it would be nice if I have to
>>>>> correct the OS clock, it would still be nice to resync Pharo with the OS,
>>>>> keep both in sync and correct. What I am wanting is simply to resync the
>>>>> Pharo clock with the OS clock.
>>>>>
>>>>> It seems that when the Pharo image is started that it gets the OS
>>>>> System time, but keeps its own time after that. Now I do not know the
>>>>> consequences of Pharo adjusting its time backward. If this isn't possible,
>>>>> then I might have to do some workarounds to insure that I get my data in a
>>>>> timely manner.
>>>>>
>>>>> The image I have been developing in is currently about 30 seconds ahead
>>>>> of the OS clock. It is on my laptop. It might be due to the laptops sleep
>>>>> and hibernation. I have not tested this on my server.
>>>>>
>>>>> That is the situation as best I know it.
>>>>>
>>>>> Thanks.
>>>>>
>>>>> Jimmie
>>>>>
>>>>>
>>>
>>>
>>
>


-- 
Mariano
http://marianopeck.wordpress.com
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