[omniORB] Setting system time

[jon.kristensen@kongsberg-simrad.com]

Sai-Lai,

Thanks for your reply.
Two additional questions?
1. Does omniORB3 behave in the same way?
2. Any reason why the scavenger does not do a 'Sleep(scan period)' instead? That
would be simpler and more safe. I do not see the reduced timing accuracy as a
problem.

Jon.





Sai-Lai Lo <S.Lo@uk.research.att.com> on 04.04.2001 13:34:13
Internet mail from:
To:   Jon Kristensen
cc:   omniorb-list@uk.research.att.com

Subject:  Re: [omniORB] Setting system time



>>>>> 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.

Sai-Lai




--
Sai-Lai Lo                                   S.Lo@uk.research.att.com
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