# Dike-0.0.4 **URL:** \ **Category:** Ruby\ **Created:** [January 9, 2008, 7:52pm UTC](https://www.ruby-forum.com/t/dike-0-0-4/125507 "2008-01-09T19:52:20Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ara\_howard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/d9b06d/32.png) [@ara\_howard](https://www.ruby-forum.com/u/ara_howard)\ **Post date:** [January 9, 2008, 7:52pm UTC](https://www.ruby-forum.com/t/dike-0-0-4/125507/1 "2008-01-09T19:52:20Z")
NAME dike SYNOPSIS a simple memory leak detector for ruby with preconfigured rails hooks. INSTALL gem install dike URIS [http://www.codeforpeople.com/lib/ruby/](http://www.codeforpeople.com/lib/ruby/) [http://rubyforge.org/projects/codeforpeople/](http://rubyforge.org/projects/codeforpeople/) DESCRIPTION the concept behind dike.rb is simple: class Object is extended in order that the location of each object’s creation is tracked. a summarizer command is given to walk ObjectSpace using each object’s class and the location if it’s creation to detect memory leaks. not all leaks can be detected and some that are may not really be leaks, but dike provided a simple way to see the hotspots in your code that may potentially be leaking. HISTORY 0.0.4: ``` - under rare circumstances dike itself interacted strangely with ``` certain classes and caused them to leak, HTTPOK was one such example. this release fixes that bug. thanks to Jan Kubr for providing a great test case that helped me fix this. EXAMPLES ### PURE RUBY ``` ## just dumping sequential snapshots to stderr, looking at a ``` specific class ``` # cfp:~ > cat sample/a.rb require 'dike' class Leak < ::String end Leaks = Array.new Dike.filter Leak loop do Leaks << Leak.new('leak' * 1024) Dike.finger sleep 1 end # cfp:~ > ruby sample/a.rb | less --- - class: Leak count: 2 trace: - sample/a.rb:11 - sample/a.rb:10:in `loop' - sample/a.rb:10 --- - class: Leak count: 3 trace: - sample/a.rb:11 - sample/a.rb:10:in `loop' - sample/a.rb:10 --- - class: Leak count: 4 trace: - sample/a.rb:11 - sample/a.rb:10:in `loop' - sample/a.rb:10 --- - class: Leak count: 5 trace: - sample/a.rb:11 - sample/a.rb:10:in `loop' - sample/a.rb:10 --- - class: Leak count: 6 trace: - sample/a.rb:11 - sample/a.rb:10:in `loop' - sample/a.rb:10 ## dumping sequential snapshots using Dike.logfactory and then ``` using the ‘dike’ command line tool to do comparisons of the dumped snapshots ``` # cfp:~ > cat sample/b.rb require 'dike' Leaks = Array.new class Leak def initialize @leak = 42.chr * (2 ** 20) end end Dike.logfactory './log/' Dike.finger 3.times{ Leaks << Leak.new } Dike.finger 2.times{ Leaks << Leak.new } Dike.finger # cfp:~ > ruby sample/b.rb # cfp:~ > ls log/ 0 1 2 # cfp:~ > dike log/ --- - class: Leak count: 3 trace: - sample/b.rb:15 - sample/b.rb:15:in `times' - sample/b.rb:15 - class: Leak count: 2 trace: - sample/b.rb:19 - sample/b.rb:19:in `times' - sample/b.rb:19 # cfp:~ > dike log/0 log/1 --- - class: Leak count: 3 trace: - sample/b.rb:15 - sample/b.rb:15:in `times' - sample/b.rb:15 # cfp:~ > dike log/1 log/2 --- - class: Leak count: 2 trace: - sample/b.rb:19 - sample/b.rb:19:in `times' - sample/b.rb:19 ``` ### RAILS ``` # cfp:~ > cat ./config/environment.rb ... require 'dike' Dike.on :rails # cfp:~ > ./script/server # cfp:~ > curl --silent http://localhost:3000 >/dev/null # cfp:~ > cat ./log/dike/0 --- - class: String count: 90769 trace: [] - class: Array count: 18931 trace: [] - class: Class count: 2 trace: - votelink.com/public/../config/../lib/widgets.rb:222:in ``` `class_factory' - votelink.com/public/../config/../lib/widgets.rb:220:in `each’ - [votelink.com/public/../config/../lib/widgets.rb:220:in](http://votelink.com/public/../config/../lib/widgets.rb:220:in) `class_factory' - votelink.com/public/../config/../lib/widgets.rb:248:in `Widget’ - [votelink.com/public/../config/../lib/widgets/page/base.rb:1](http://votelink.com/public/../config/../lib/widgets/page/base.rb:1) - [votelink.com/public/../config/../lib/widgets.rb:31:in](http://votelink.com/public/../config/../lib/widgets.rb:31:in) `require' - votelink.com/public/../config/../lib/widgets.rb:31:in `load’ - [votelink.com/public/../config/../lib/widgets.rb:16:in](http://votelink.com/public/../config/../lib/widgets.rb:16:in) `for_controller' - votelink.com/public/../config/../lib/widgets.rb:243:in `widget’ - [votelink.com/public/../config/../app/controllers/](http://votelink.com/public/../config/../app/controllers/) application.rb:150 … ``` # cfp:~ > curl --silent http://localhost:3000 >/dev/null # cfp:~ > cat ./log/dike/1 --- - class: String count: 100769 trace: [] - class: Array count: 19931 trace: [] - class: Class count: 5 trace: - votelink.com/public/../config/../lib/widgets.rb:222:in ``` `class_factory' - votelink.com/public/../config/../lib/widgets.rb:220:in `each’ - [votelink.com/public/../config/../lib/widgets.rb:220:in](http://votelink.com/public/../config/../lib/widgets.rb:220:in) `class_factory' - votelink.com/public/../config/../lib/widgets.rb:248:in `Widget’ - [votelink.com/public/../config/../lib/widgets/page/base.rb:1](http://votelink.com/public/../config/../lib/widgets/page/base.rb:1) - [votelink.com/public/../config/../lib/widgets.rb:31:in](http://votelink.com/public/../config/../lib/widgets.rb:31:in) `require' - votelink.com/public/../config/../lib/widgets.rb:31:in `load’ - [votelink.com/public/../config/../lib/widgets.rb:16:in](http://votelink.com/public/../config/../lib/widgets.rb:16:in) `for_controller' - votelink.com/public/../config/../lib/widgets.rb:243:in `widget’ - [votelink.com/public/../config/../app/controllers/](http://votelink.com/public/../config/../app/controllers/) application.rb:150 … ``` # cfp:~ > dike ./log/dike ... - class: Class count: 3 trace: - votelink.com/public/../config/../lib/widgets.rb:222:in ``` `class_factory' - votelink.com/public/../config/../lib/widgets.rb:220:in `each’ - [votelink.com/public/../config/../lib/widgets.rb:220:in](http://votelink.com/public/../config/../lib/widgets.rb:220:in) `class_factory' - votelink.com/public/../config/../lib/widgets.rb:248:in `Widget’ - [votelink.com/public/../config/../lib/widgets/page/base.rb:1](http://votelink.com/public/../config/../lib/widgets/page/base.rb:1) - [votelink.com/public/../config/../lib/widgets.rb:31:in](http://votelink.com/public/../config/../lib/widgets.rb:31:in) `require' - votelink.com/public/../config/../lib/widgets.rb:31:in `load’ - [votelink.com/public/../config/../lib/widgets.rb:16:in](http://votelink.com/public/../config/../lib/widgets.rb:16:in) `for_controller' - votelink.com/public/../config/../lib/widgets.rb:243:in `widget’ - [votelink.com/public/../config/../app/controllers/](http://votelink.com/public/../config/../app/controllers/) application.rb:150 … NOTES - the ‘Dike.finger’ method dumps it’s log in a format showing - loading into a rails environment causes snapshots of the above format to be dumped into RAILS\_ROOT/log/dike/ after each request. each snapshot is incrementally numbered 0, 1, … - the ‘dike’ command line tool can be used in two ways - options that affect logging LIMITATIONS not all object creation can be tracked. not all leaks are reported. some reported leaks are not. dike shows you where in the source objects are being created that cannot be reclaimed - these are not always leaks as this line ``` class C; end ``` shows. the class ‘C’ cannot be reclaimed and yet is not a leak. AUTHOR ara [dot] t [dot] howard [at] gmail [dot] com enjoy! a @ [http://codeforpeople.com/](http://codeforpeople.com/) ---
**Author:** ![ara\_howard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/d9b06d/32.png) [@ara\_howard](https://www.ruby-forum.com/u/ara_howard)\ **Post date:** [January 9, 2008, 8:28pm UTC](https://www.ruby-forum.com/t/dike-0-0-4/125507/2 "2008-01-09T20:28:11Z")
On Jan 9, 2008, at 10:51 , ara howard wrote: > ``` > loop do > Leaks << Leak.new('leak' * 1024) > Dike.finger > sleep 1 > end > > ``` Shouldn’t that be DutchBoy instead of Dike? 😛 ---
**Author:** ![ara\_howard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/d9b06d/32.png) [@ara\_howard](https://www.ruby-forum.com/u/ara_howard)\ **Post date:** [January 9, 2008, 8:34pm UTC](https://www.ruby-forum.com/t/dike-0-0-4/125507/3 "2008-01-09T20:34:38Z")
On Jan 9, 2008, at 12:27 PM, Ryan D. wrote: > Shouldn’t that be DutchBoy instead of Dike? it’s a library for the ladies 😉 a @ [http://codeforpeople.com/](http://codeforpeople.com/) ---
**Author:** ![ara\_howard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/d9b06d/32.png) [@ara\_howard](https://www.ruby-forum.com/u/ara_howard)\ **Post date:** [January 11, 2008, 5:35pm UTC](https://www.ruby-forum.com/t/dike-0-0-4/125507/4 "2008-01-11T17:35:44Z")
On 9 ene, 19:51, ara howard [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ``` > # cfp:~ > cat ./log/dike/0 > --- > - class: String > count: 90769 > trace: [] > - class: Array > count: 18931 > trace: [] > > ``` So how do you interpret these kinds of results with empty stack traces? So you know a bunch of String and Array objects are being created and aren’t going to be collected, at least at the point where you called Dike.finger, but you don’t know where they were created (admittedly, there are so many of them it probably wouldn’t help you much to know that they were being created “all over the place”). Cheers, Wincent ---
**Author:** ![ara\_howard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/d9b06d/32.png) [@ara\_howard](https://www.ruby-forum.com/u/ara_howard)\ **Post date:** [January 11, 2008, 5:59pm UTC](https://www.ruby-forum.com/t/dike-0-0-4/125507/5 "2008-01-11T17:59:59Z")
On Jan 11, 2008, at 9:35 AM, Wincent C. wrote: > So how do you interpret these kinds of results with empty stack > traces? So you know a bunch of String and Array objects are being > created and aren’t going to be collected, at least at the point where > you called Dike.finger, but you don’t know where they were created > (admittedly, there are so many of them it probably wouldn’t help you > much to know that they were being created “all over the place”). dike does what it can to track the object lifecycle, but certain things cannot be traced to a specific file:line. for instance string = “literal” array = [:literal] does not trigger Class.new, Class.allocate, or Object#initialze to be triggered (in ruby) and this is the main mechanism for dike to track objects. dike tracks objects per class per stacktrace so it knows about the Leak objects coming from file a.rb, line 42, for example. so certain objects cannot be tracked. it’s a good reason to prefer Hash.new over {} though 😉 if they could be tracked it wouldn’t be an issue that they were ‘all over the place’ since the dike commandline tool provides a way to compare one dump to the next, showing only leaks in the output and ignoring those entries that are not leaks. in the end it’s a limitation of dike. nonetheless, i’ve been able to reduce memory leaks in many rails apps in 30 minutes of work using dike.rb, so it is not without it’s usefulness. also, note that even a c instrumented object cycle tracker will fail to detect things like void \*leak(){ return malloc(42) } in a c extension - all the tools have their limits. for ruby i think starting with something like dike.rb, moving up to something like bleakhouse, with it’s custom ruby, and finally moving on to c only tools is a logical process to follow. another very important technique is, as much as possible, to use binary search on your code you determine leaks: hack your code so the back 50% of it doesn’t run - test for the leak - then adjust up or down based on what you find. this along can narrow down on the leaking bits of code _very_ quickly. then a tool like dike.rb can identify the exact lines. it all starts feeling like we are back to c++ doesn’t it 😉 cheers