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I'm programming in Ruby (although it's probably not very relevant), and dealing with some quite large data sets. As a consequence, some of my variables might be quite large.

Once I no longer need a variable, is there any advantage to removing it? Would this potentially free some RAM or have any other advantage?

Sparhawk
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    Objects will be garbage collected if they are no longer referenced by a variable or another object, but Ruby processes don't release memory back to the OS once it has been allocated (this may be different in JRuby). – Zach Kemp Sep 12 '13 at 05:33

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Yes. It will free some RAM to be used within the program, and speeds up other operations. That is what Garbage Collection is for.

sawa
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  • Are you saying that I need to explicitly remove a variable in order to allow it to be garbage collected? (i.e. the opposite of Zach Kemp's comment?) – Sparhawk Sep 12 '13 at 05:58
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    A variable is not an object, it refers to an object. If you remove all the references to an object, that object is garbage collected unless it is not of specific class (fixnum, symbol, etc.). This is compatible with what Zach Kemp says. – sawa Sep 12 '13 at 06:07
  • Ah, that makes sense. I get quite confused with objects vs. variables in Ruby. I just realised that I'm using a local variable, which apparently [cannot be removed](http://stackoverflow.com/a/2012125/1944384). Thus, should I assign something small like nil to it instead? – Sparhawk Sep 12 '13 at 06:44
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    A local variable only remains within the scope (such as method definition or block), so you usually don't need to care about it, but if that is not the case, assigning it to something else will be a good idea. Whether the referent is small or not does not matter as long as it already exists because reference is only a pointer. – sawa Sep 12 '13 at 06:47
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If you are wanting to 'manually garbage collect', you could look into the Ojbect#remove_instance_variable method, which will change the value to nil as you mention, and it returns the removed data, which I suppose could be helpful for any post-op processing.

http://ruby-doc.org/core-2.0.0/Object.html#method-i-remove_instance_variable

Steve Benner
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  • Thanks, I knew how to remove variables (although mine was a local variable), but I wasn't sure when I should do this. – Sparhawk Sep 13 '13 at 06:47