[omniORB] Setting system time

[Cary O'Brien]

> >>>>> jon kristensen writes:
> 
> > I recently discovered that omniORB 2.8.0 gets into trouble if the system time
> > changes. I found that the scavenger thread seems to use a timed wait, where it
> > just adds a period to an accumulated time value, and waits for the system time
> > to reach that value. If I adjust the system time forward, the scavenger will run
> > in an endless loop until the accumulated time value catches up. Opposite, if I
> > set the time backwards, the scavenger thread will wait (not run) until the
> > system time reaches the value it had before it was set. See
> > orbCore/scavenger.cc, omniORB_Scavenger::run_undetached().
> 
> > Am I correct?
> 
> I think that is the expected behaviour. The pthread conditional variable
> timed_wait takes a time argument which is the absolute time, as opposite to
> a relative period from now, this is why you are seeing the behaviour.
> 
> > Are there any other places in the omniORB code that behaves like this?
> 
> No, the scavenger is the only thread that do the periodic housekeeping. 
> 
> > The reason for my concern is that I synchronize the clocks of all my
> > computers to GPS time (UTC). Invariantly this my cause a large time jump,
> > especially if one of the machines for some reason was not set correctly.
> 
> I don't know what you can do about the system time going backward. As for
> the system time going forward, you can modify the scavenger code to use
> omni_thread::get_time to get the time now and then add to it the scan period.
> 

I think NTP will adjust the clock by speeding it up/slowing it down
rather than making abrupt changes.  Does this help?

ntp: http://www.eecis.udel.edu/~ntp

-- cary

> Sai-Lai
> 
> 
> 
> 
> -- 
> Sai-Lai Lo                                   S.Lo@uk.research.att.com
> AT&T Laboratories Cambridge           WWW:   http://www.uk.research.att.com 
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