Regenerate Shotwell thumbnails in parallell processing

shotwell-thumbnailer

#!/bin/bash

THUMB_ROOT=~/.cache/shotwell/thumbs
MAX_PROCESSES=4
i=0

sqlite3 ~/.local/share/shotwell/data/photo.db \
  "select id||' '||filename from PhotoTable order by exposure_time desc" |

while read id filename; do
  let i++
  tf1=$(printf $THUMB_ROOT/thumbs128/thumb%016x.jpg $id);
  tf2=$(printf $THUMB_ROOT/thumbs360/thumb%016x.jpg $id);
  if [ -e "$tf1" ]
  then
    echo "Skipping $filename"
  else
    echo "Generating thumb for $filename";
    convert "$filename" -quality 60 -auto-orient -thumbnail 128x128 $tf1 &
    convert "$filename" -quality 60 -auto-orient -thumbnail 360x360 $tf2 &
    if [ $(($i % (MAX_PROCESSES/2))) == 0 ]
    then
        wait
    fi
  fi
done