[Twisted-Python] a question about monotonic clock

[exarkun at twistedmatrix.com]

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.

Jean-Paul