Misfeature in uucp polling mechanism

[Stephen J. Friedl]

Howdy folks,

     Those using the /usr/lib/uucp/Poll file to regularly talk to
other machines may notice that there are *two* calls per poll
hour rather than the one that we would expect.   If you don't
like this, check out root's crontab for the two lines:

        1,30 * * * * /usr/lib/uucp/uudemon.poll > /dev/null
        41,11 * * * * /usr/lib/uucp/uudemon.hour > /dev/null

The first (uudemon.poll) runs through the /usr/lib/uucp/Poll file
and queues up an empty job (with sequence number 0000) for each
machine that is supposed to be called this hour, but it does not
actually make the call.  Then, uudemon.hour runs shortly
thereafter and calls all machines that have any traffic (i.e.,
real mail or an empty job).

Most of the time we want to transfer real mail as soon as
possible, and uudemon.hour will try twice per hour until it gets
through (subject, of course, to uucico retry limitations).

For routine polling without real traffic, however, twice per hour
is probably too often, but that's what uudemon.poll is doing
here.  During a typical hour:

        xx:01   uudemon.poll queues up an empty job
        xx:11   uudemon.hour calls up all sites with traffic
        xx:30   uudemon.poll queues up an empty job         <--- bug bug bug
        xx:41   uudemon.hour calls up all sites with traffic

Dropping the uudemon.poll at 30 minutes after the hour will not
queue up the empty job, and now polling will be done once per
hour.

Remember, excess phone calls are kind of like a tax, and *poll*
taxes are unconstitutional :-).

     Steve

-- 
Stephen J. Friedl / V-Systems, Inc. / Santa Ana, CA / +1 714 545 6442 
3B2-kind-of-guy   / friedl at vsi.com  / {attmail, uunet, etc}!vsi!friedl

"I'm making a fashion statement: I'm saying I don't know how to dress." - me