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Re: Running N jobs from M all the time
- X-seq: zsh-users 2676
- From: "Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxxxxxxxxx>
- To: Szabolcs Szakacsits <szaka@xxxxxxxxx>, zsh-users@xxxxxxxxxxxxxx
- Subject: Re: Running N jobs from M all the time
- Date: Tue, 12 Oct 1999 15:59:01 +0000
- In-reply-to: <Pine.LNX.4.10.9910120601180.1839-100000@xxxxxxxxxxxxxxxxxxxx>
- Mailing-list: contact zsh-users-help@xxxxxxxxxxxxxx; run by ezmlm
- References: <Pine.LNX.4.10.9910120601180.1839-100000@xxxxxxxxxxxxxxxxxxxx>
On Oct 12, 6:38am, Szabolcs Szakacsits wrote:
} Subject: Running N jobs from M all the time
}
} My question would be there is an easy way for $SUBJECT?
If I'm understanding you correctly, you want to do something like
repeat 1000 do
if (( number_of_jobs >= number_of_processors )); then
wait $any_job
fi
command &
done
And the complaint is that "wait" can only wait for one specific job or
for all of them, not for "the next one that exits."
} I know this can be done with ps, grep, wait, etc but a bit painful and
} not elegant/modern I'd like to use a cleaner way.
You've just discovered another use for the coprocess. The rest of this
is just standard parallel programming stuff.
function run_parallel {
# Runs N copies of command at once until M copies have run.
emulate -L zsh
if (( $# < 3 )); then
print "usage: run_parallel N M command [args ...]" >&2
return 1
fi
integer N=$1 M=$2
shift 2
if ((M <= N)); then
repeat $M do $==* & done
wait
else
# Set up a loop to read and write one byte at a time. This
# semaphores between the parallel children and the parent zsh.
# It's important to pass exactly one byte here and not rely on
# reading complete lines, lest a race condition develop.
# Unfortunately, a race still can occur, it's just less likely.
# Maybe SMP systems are better about multiple writers on one FD?
coproc while ((--M > 0)) && read -u0k; do print -n .; done
# Start the first N children
repeat $N do
((--M))
{ $==* ; print -np . } &
done
# Wait for the semaphore from each child and start another as
# soon as we get it, up to M children.
while ((--M > 0)) && read -pk; do
{ $==* ; print -np . } &
done
# Wait for the last N semaphores.
repeat $N do read -pk; done
fi
return $?
}
--
Bart Schaefer Brass Lantern Enterprises
http://www.well.com/user/barts http://www.brasslantern.com
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