set correct number of cores before runnning via set.cores()
find range in file:
whisper-dump.py collectd/host/cpu-0/cpu-user/value.wsp | grep -E '^[[:digit:]]+'| cut -f 2 -d ' ' | sort -n | head
whisper-dump.py collectd/host/cpu-0/cpu-user/value.wsp | grep -E '^[[:digit:]]+'| cut -f 2 -d ' ' | sort -n | tail
whisper]$ find -name '*.wsp' | parallel --gnu ~/extract-one.sh 1410772800 1410783600 /tmp/whisper-export/ {}