Add memory leak example.

examples/memory/leak.rb

@@ -0,0 +1,40 @@
+#!/usr/bin/env ruby
+
+require 'vips'
+require 'objspace'
+
+repeat = 100
+
+def rss
+	`ps -o rss= -p #{$$}`.chomp.to_i/1024
+end
+
+# Doesn't seem to have any affect:
+Vips.cache_set_max(0)
+Vips.cache_set_max_mem(0)
+
+GC.start
+puts "RSS at startup with gems loaded: %d MB" % [rss]
+
+if ARGV.empty?
+	# A 4MiB JPEG, which decompresses to a 32MiB pixel buffer.
+	ARGV << "../../spec/vips/thumbnail/IMG_8537.jpg"
+end
+
+repeat.times do |i|
+	ARGV.each do |filename|
+		img = Vips::Image.new_from_file filename, :access => :sequential
+		img.write_to_file 'test.jpg', :Q => 50
+
+		# Try various permutations of these:
+		# img.close
+		# img = nil
+		# GC.start
+
+		print "\rIteration: %-8d RSS: %6d MB File: %-32s".freeze % [i+1, rss, filename]
+	end
+end
+puts
+
+GC.start
+puts "RSS at exit: %d MB" % [rss]