Watch JVM heap utilization

heapwatcher.rb

#!/usr/bin/env ruby

## run like: tail --lines=0 --follow=name /var/log/tomcat6/gc.log | this_ruby_script

ARGF.each do |line|
  if match = /secs\]\s\d+K-\>(\d+)K\((\d+)K\)/.match(line)
    heap_cur = match[1]
    heap_lim = match[2]
    heap_pct = heap_cur.to_f / heap_lim.to_f * 100.0
    puts "#{heap_cur} / #{heap_lim} KiB : #{heap_pct}%"
  end
end