# Memory Leaks: How to see GC Roots? **URL:** \ **Category:** Ruby\ **Created:** [December 1, 2005, 5:02pm UTC](https://www.ruby-forum.com/t/memory-leaks-how-to-see-gc-roots/49225 "2005-12-01T17:02:07Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![schween](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@schween](https://www.ruby-forum.com/u/schween)\ **Post date:** [December 1, 2005, 5:02pm UTC](https://www.ruby-forum.com/t/memory-leaks-how-to-see-gc-roots/49225/1 "2005-12-01T17:02:07Z")
Hello! Is there a way to get a list of all GC roots in my Ruby program? I know there is a memory leak somewhere in my application, I just don’t know in which part. Listing all variables on the Heap becomes too large, but just seeing the GC roots would be a great help. Can you suggest some ideas? Best wishes, Sven C. Koehler ---
**Author:** ![schween](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@schween](https://www.ruby-forum.com/u/schween)\ **Post date:** [December 1, 2005, 5:14pm UTC](https://www.ruby-forum.com/t/memory-leaks-how-to-see-gc-roots/49225/2 "2005-12-01T17:14:17Z")
Sven C. Koehler wrote: > Hello! > > Is there a way to get a list of all GC roots in my Ruby program? I > know there is a memory leak somewhere in my application, I just don’t > know in which part. Listing all variables on the Heap becomes too > large, but just seeing the GC roots would be a great help. Can you > suggest some ideas? I don’t think this info is available. But how about statistics per class? That way you can at least determine which class is responsible for the massive object count. 17:09:39 [source]: ruby -r pp -e ‘c=Hash.new(0); ObjectSpace.each\_object {|obj| c[obj.class]+=1}; pp c.sort\_by {|k,v| -v}’ [[String, 582], [Class, 185], [Module, 18], [Array, 8], [Float, 6], [Regexp, 6], [Object, 3], [IO, 3], [File, 2], [NoMemoryError, 1], [SystemStackError, 1], [Binding, 1], [fatal, 1], [ThreadGroup, 1], [Hash, 1], [Thread, 1]] Kind regards ``` robert ``` ---
**Author:** ![schween](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@schween](https://www.ruby-forum.com/u/schween)\ **Post date:** [December 1, 2005, 10:19pm UTC](https://www.ruby-forum.com/t/memory-leaks-how-to-see-gc-roots/49225/3 "2005-12-01T22:19:12Z")
Sven C. Koehler wrote: > Hello! > > Is there a way to get a list of all GC roots in my Ruby program? I know > there is a memory leak somewhere in my application, I just don’t know in > which part. Listing all variables on the Heap becomes too large, but just > seeing the GC roots would be a great help. Can you suggest some ideas? > > Best wishes, > > Sven C. Koehler There’s a ruby patch to show what objects are reachable from the roots (and the chain of references in each case): [http://blade.nagaokaut.ac.jp/cgi-bin/vframe.rb/ruby/ruby-talk/151854?151368-152549](http://blade.nagaokaut.ac.jp/cgi-bin/vframe.rb/ruby/ruby-talk/151854?151368-152549) It should easy to modify it to just show the roots. ---
**Author:** ![schween](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@schween](https://www.ruby-forum.com/u/schween)\ **Post date:** [December 2, 2005, 5:37pm UTC](https://www.ruby-forum.com/t/memory-leaks-how-to-see-gc-roots/49225/4 "2005-12-02T17:37:08Z")
On Fri, Dec 02, 2005 at 06:18:57AM +0900, Joel VanderWerf wrote: > There’s a ruby patch to show what objects are reachable from the roots > (and the chain of references in each case): > > [http://blade.nagaokaut.ac.jp/cgi-bin/vframe.rb/ruby/ruby-talk/151854?151368-152549](http://blade.nagaokaut.ac.jp/cgi-bin/vframe.rb/ruby/ruby-talk/151854?151368-152549) > > It should easy to modify it to just show the roots. I tried to use the patch with Ruby 1.8.3 and the current CVS Trunk snapshot as of today (2005-12-02). With Ruby 1.8.3 I had to adjust the rb\_sprintf calls to use snprintf. In order to use the patch with the current Trunk, I had to apply part of the patch by hand. However, I got no usable output by trying to use it on both versions, so I don’t know whether the patch is actually able to access the GC roots. The output looks on both ruby 1.8.3 and the CVS Trunk as this: irb(main):001:0\> $a = File.open(“fo”, “w”) =\> #\ irb(main):002:0\> $b = [$a] =\> [#\] irb(main):003:0\> GC.reachability\_paths($a) (irb):3: warning: Checking frame stack… (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: Checking ruby\_class… (irb):3: warning: Checking ruby\_scope… (irb):3: warning: Checking save\_regs\_gc\_mark… (irb):3: warning: Checking stack\_start… (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: …found, after 0 steps! (irb):3: warning: Checking threads… (irb):3: warning: Checking C globals… (irb):3: warning: Checking end\_proc… (irb):3: warning: Checking global\_tbl… (irb):3: warning: Checking class\_tbl… (irb):3: warning: …found, after 0 steps! (irb):3: warning: Checking trap\_list… (irb):3: warning: Checking generic\_ivar\_tbl… (irb):3: warning: Checking mark parser… (irb):3: warning: Checking mark stack… (irb):3: warning: Unmarking… (irb):3: warning: Done. =\> [[], [], [], [], [], [], [], [], [], [], []] I would have expected $a to be reachable via $b. Best wishes, Sven C. Koehler ---
**Author:** ![schween](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@schween](https://www.ruby-forum.com/u/schween)\ **Post date:** [December 2, 2005, 6:25pm UTC](https://www.ruby-forum.com/t/memory-leaks-how-to-see-gc-roots/49225/5 "2005-12-02T18:25:53Z")
In message [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid), Sven C. Koehler [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes > Is there a way to get a list of all GC roots in my Ruby program? I know > there is a memory leak somewhere in my application, I just don’t know in > which part. Listing all variables on the Heap becomes too large, but just > seeing the GC roots would be a great help. Can you suggest some ideas? If you are on Windows then Ruby Memory Validator can do this. ``` http://www.softwareverify.com ``` Stephen