'hpc' in the shell - starts a maximum of n compute commands modulo n controlled in parallel, using make

echo -n 'targets = $(subst .png,.jpg,$(wildcard *.png))\n$(targets):\n convert $(subst .jpg,.png,$@) $@ \nall : $(targets)' | make -j 4 -f - all
this oneliner uses make and it's jobserver for parallel execution of your script. The '-j' flag for make defines number of subprocesses to launch, '-f' tells make use stdin instead of Makefile. Also make have neat flag '-l', which "Specifies that no new jobs (commands) should be started if there are others jobs running and the load is at least load (a floating-point number)." Also you can use plain Makefile, for better readability: targets = $(subst .png,.jpg,$(wildcard *.png)) (targets): echo convert $(subst .jpg,.png,$@) $@ all : $(targets)

5
By: mechmind
2010-07-15 07:19:17

1 Alternatives + Submit Alt

  • the block of the loop is useful whenever you have huge junks of similar jobs, e.g., convert high res images to thumbnails, and make usage out of all the SMP power on your compute box without flooding the system. note: c is used as counter and the random sleep r=`echo $RANDOM%5 |bc`; echo "sleep $r"; sleep $r is just used as a dummy command. Show Sample Output


    5
    c=0; n=8; while true; do r=`echo $RANDOM%5 |bc`; echo "sleep $r"; sleep $r& 2>&1 >/dev/null && ((c++)); [ `echo "$c%$n" | bc` -eq 0 ] && echo "$c waiting" && wait; done
    cp · 2010-07-08 13:56:28 1

What Others Think

@mechmind do you have a make solution when it becomes recursive?
cp · 414 weeks and 4 days ago

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