Convenient way to get GC stats for a block of Ruby code.

gc_stat.rb

def gc_stat
  GC.disable

  asym = :total_allocated_objects
  fsym = :total_freed_objects

  before = GC.stat
  ba = before[asym]
  bf = before[fsym]
  puts "Before: alloc=#{ba} free=#{bf}"
  
  start = Time.now

  ret = yield
  
  elapsed = Time.now - start

  after = GC.stat  
  aa = after[asym]
  af = after[fsym]

  puts "After: alloc=#{aa} free=#{af}"
  puts "Delta: alloc=#{aa - ba} free=#{af - bf} elapsed=#{elapsed}"

  GC.enable

  ret
end