[Twisted-Python] a question about monotonic clock

gelin yan dynamicgl at gmail.com
Mon Oct 29 03:09:14 EDT 2012


On Sun, Oct 28, 2012 at 11:22 PM, Christopher Armstrong <
radix at twistedmatrix.com> wrote:

> On Sun, Oct 28, 2012 at 1:28 PM, <exarkun at twistedmatrix.com> wrote:
>
>> On 05:57 am, dynamicgl at gmail.com wrote:
>> >Hi All
>> >
>> >    I am quite concerned the ticket 2424 due to our system use
>> >reactor.callLater almost anywhere. I know this issue is hard to be
>> >finxed
>> >otherwise It wouldn't exist for such a long time. So any work around
>> >before
>> >we getting fix it? The only way I can do is to disable NTP or stop
>> >process,
>> >sync the time manually and then restart the process. The latter way is
>> >hard
>> >to be accepted due to we have many machines.
>>
>> NTP does not cause problems with scheduling.  NTP gradually slews the
>> system clock - it does not introduce discontinuities (either forward or
>> backward), it changes the rate at which time passes until the system
>> clock agrees with the external clock.
>>
>> If you have systems configured to have their system clocks jump
>> (`ntpdate` is sometimes used for this), fix them to not be configured
>> this way.
>>
>> #2424 is primarily about user-initiated events, primarily on desktop
>> machines - a user changing the system time, a user suspending the
>> machine (and later unsuspending it).  There's little or no reason for
>> problems related to #2424 to ever come up on a properly maintained
>> server.
>>
>>
> I think that for *certain* uncommon types of applications, even the very
> minor skewing of ntp can cause problems, but I wonder if gelin yan has
> encountered real problems caused by the ntp skewing in the application
> under discussion. Gelin, you did not describe what problem you're actually
> having. If you would, that would benefit the continuation of the discussion.
>
> --
> Christopher Armstrong
> http://radix.twistedmatrix.com/
> http://planet-if.com/
>
>
>
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>
Hi Christopher

   I didn't encounter any problem with twisted so far but it happened a few
years ago when I deployed the system (based on C#/C++) on windows.
Sometimes, the timer stopped running.

    Bugs triggered by this issue are not really easy to be detected. That
is why I am concerned.
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