在 Ruby 中查找内存泄漏的原因

我在Rails代码中发现了内存泄漏——也就是说，我发现了what个代码泄漏，但没有发现why个.我将其简化为一个不需要Rails的测试用例:

require 'csspool'
require 'ruby-mass'

def report
    puts 'Memory ' + `ps ax -o pid,rss | grep -E "^[[:space:]]*#{$$}"`.strip.split.map(&:to_i)[1].to_s + 'KB'
    Mass.print
end

report

# note I do not store the return value here
CSSPool::CSS::Document.parse(File.new('/home/jason/big.css'))

ObjectSpace.garbage_collect
sleep 1

report

ruby-mass应该可以让我看到记忆中的所有对象.CSSPool是基于racc的CSS解析器/家/杰森/大.css是a 1.5MB CSS file.

这将产生:

Memory 9264KB

==================================================
 Objects within [] namespace
==================================================
  String: 7261
  RubyVM::InstructionSequence: 1151
  Array: 562
  Class: 313
  Regexp: 181
  Proc: 111
  Encoding: 99
  Gem::StubSpecification: 66
  Gem::StubSpecification::StubLine: 60
  Gem::Version: 60
  Module: 31
  Hash: 29
  Gem::Requirement: 25
  RubyVM::Env: 11
  Gem::Specification: 8
  Float: 7
  Gem::Dependency: 7
  Range: 4
  Bignum: 3
  IO: 3
  Mutex: 3
  Time: 3
  Object: 2
  ARGF.class: 1
  Binding: 1
  Complex: 1
  Data: 1
  Gem::PathSupport: 1
  IOError: 1
  MatchData: 1
  Monitor: 1
  NoMemoryError: 1
  Process::Status: 1
  Random: 1
  RubyVM: 1
  SystemStackError: 1
  Thread: 1
  ThreadGroup: 1
  fatal: 1
==================================================

Memory 258860KB

==================================================
 Objects within [] namespace
==================================================
  String: 7456
  RubyVM::InstructionSequence: 1151
  Array: 564
  Class: 313
  Regexp: 181
  Proc: 113
  Encoding: 99
  Gem::StubSpecification: 66
  Gem::StubSpecification::StubLine: 60
  Gem::Version: 60
  Module: 31
  Hash: 30
  Gem::Requirement: 25
  RubyVM::Env: 13
  Gem::Specification: 8
  Float: 7
  Gem::Dependency: 7
  Range: 4
  Bignum: 3
  IO: 3
  Mutex: 3
  Time: 3
  Object: 2
  ARGF.class: 1
  Binding: 1
  Complex: 1
  Data: 1
  Gem::PathSupport: 1
  IOError: 1
  MatchData: 1
  Monitor: 1
  NoMemoryError: 1
  Process::Status: 1
  Random: 1
  RubyVM: 1
  SystemStackError: 1
  Thread: 1
  ThreadGroup: 1
  fatal: 1
==================================================

你可以看到记忆上升了way.一些计数器上升，但不存在特定于CSSPool的对象.我使用ruby mass的"索引"方法来判断包含以下引用的对象:

Mass.index.each do |k,v|
    v.each do |id|
        refs = Mass.references(Mass[id])
        puts refs if !refs.empty?
    end
end

但再一次，这并没有给我任何与CSSPool相关的信息，只是gem信息之类的.

我也试过输出"GC.stat"...

puts GC.stat
CSSPool::CSS::Document.parse(File.new('/home/jason/big.css'))
ObjectSpace.garbage_collect
sleep 1
puts GC.stat

结果:

{:count=>4, :heap_used=>126, :heap_length=>138, :heap_increment=>12, :heap_live_num=>50924, :heap_free_num=>24595, :heap_final_num=>0, :total_allocated_object=>86030, :total_freed_object=>35106}
{:count=>16, :heap_used=>6039, :heap_length=>12933, :heap_increment=>3841, :heap_live_num=>13369, :heap_free_num=>2443302, :heap_final_num=>0, :total_allocated_object=>3771675, :total_freed_object=>3758306}

据我所知，如果一个对象没有被引用，并且发生了垃圾收集，那么应该从内存中清除该对象.但这里似乎不是这样.

我也读过关于C级内存泄漏的文章，由于CSSPool使用的是使用C代码的Racc，我认为这是一种可能性.我已经通过Valgrind运行了我的代码:

valgrind --partial-loads-ok=yes --undef-value-errors=no --leak-check=full --fullpath-after= ruby leak.rb 2> valgrind.txt

结果是here.我不确定这是否证实了C级泄漏，因为我还读到Ruby使用Valgrind不理解的内存进行操作.

使用的版本:

• Ruby 2.0.0-p247(我的Rails应用程序就是这样运行的)
• Ruby 1.9.3-p392-ref(用于使用Ruby mass进行测试)
• Ruby 质量0.1.3
• CS4.0.0从here开始
• CentOS 6.4和Ubuntu 13.10