Initial commit

.gitignore

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+# Ignore OSX dir files
+.DS_Store
+
+# Ignore Vim swap files
+*.swp
+

001_gc.rb

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+#!/usr/bin/ruby
+
+require 'benchmark'
+
+no_gc = ARGV[0] == '-o'
+
+num_rows = 100_000
+num_cols = 10
+
+data = Array.new(num_rows) do
+  Array.new(num_cols) { 'x' * 1000 }
+end
+
+mem_before = "%d MB" % (`ps -o rss= -p #{Process.pid}`.to_i / 1024)
+
+GC.disable if no_gc
+time = Benchmark.realtime do
+  csv = data.map do |row|
+    row.join(',')
+  end.join("\n")
+end
+
+mem_after = "%d MB" % (`ps -o rss= -p #{Process.pid}`.to_i / 1024)
+
+puts "Time: #{time} (GC #{no_gc ? 'disabled' : 'enabled'})"
+puts "MEM: #{mem_before} -> #{mem_after}"
+

002_memory.rb

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+#!/usr/bin/ruby
+
+require 'benchmark'
+
+num_rows = 100_000
+num_cols = 10
+
+data = Array.new(num_rows) do
+  Array.new(num_cols) { 'x' * 1000 }
+end
+
+mem_before = "%d MB" % (`ps -o rss= -p #{Process.pid}`.to_i / 1024)
+
+time = Benchmark.realtime do
+  csv = ''
+  num_rows.times do |i|
+    num_cols.times do |j|
+      csv << data[i][j]
+      csv << ',' unless j == num_cols - 1
+    end
+
+    csv << "\n" unless i == num_rows - 1
+  end
+end
+
+mem_after = "%d MB" % (`ps -o rss= -p #{Process.pid}`.to_i / 1024)
+
+puts "Time: #{time}"
+puts "MEM: #{mem_before} -> #{mem_after}"
+

README.md

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+# Ruby Performance Optimization Book Examples
+
+## Try to disable GC and define memory consumption
+
+1. GC often makes Ruby slow (especialy <= v2.0 ). And that's because of high memory consumption
+2. Ruby has significant memory overhead
+3. GC in v2.1+ is 5 times faster!
+4. Raw performance of v1.9 - v2.3 is about the same
+
+See [001_gc.rb].
+
+## Try to optimize memory
+
+1. 80% of performance optimization comes from memory optimization
+
+See [002_memory.rb]
+