On Mon, 28 Jan 2013 22:45:31 -0800
Dennis Peterson articulated:
> Bill Landry's unofficial sigs script does it right by using a random
> function as an offset from cron time to actually initial a sig
> download. For those of us with a couple dozen or more systems this is
> a mirror-friendly way of not getting into lockstep with any
> fixed-offset scheme. Here is the code segment from Bill's script and
> I recommend something like it.
>
> if [ -n "$RANDOM" ]
> then
> sleep_time=$(($RANDOM * $(($max_sleep_time -
> $min_sleep_time)) / 32767 + $min_sleep_time))
> else
> sleep_time=0
> while [ "$sleep_time" -lt "$min_sleep_time" -o
> "$sleep_time" -gt "$max_sleep_time" ] ; do
> sleep_time=`head -1 /dev/urandom | cksum | awk '{print
> $2}'` done
> fi
>
> A bit of precision overkill given there are only 3600 seconds in an
> hour, but it works. I use sleep $[ RANDOM % 900 ] and I have no idea
> nor care when the signature download actually begins, but every
> machine's crontab starts at the same time. The important thing to
> remember here is there is a finite amount of time required to dl all
> the sigs so regardless of the start time there will be overlap with
> other clients just because there are more clients than there are
> seconds in an hour.
I use a much simpler function:
function get_files ()
{
# This is the "snooze" test. It will delay the start of a download session
# between 0 and 546 seconds (Roughly 9 minutes). It will only work when the
# script is run via CRON. The variable $REST activates this function.
# See if the variable 'REST' has been set or if forcing it from command line
# And if we are running via CRON
if [ ${REST} -gt 0 -a ! -t 0 ]; then
# Use the BASH RANDOM function to generate a random number between 0 & 32767
RESTING=$((RANDOM/60))
sleep ${RESTING}
fi
...
}
I never saw the benefit of expanding the time span, although it could
be done easily enough.
--
Jerry ♔
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