From: Joel VanderWerf <vjoel@...>
Date: 2003-11-08T06:51:00+09:00
Subject: Re: Long-running daemon acquiring giant memory footprint

Jason DiCioccio wrote:
> I have written a long-running daemon in ruby to handle dynamic DNS 
> updates. I have just recently moved it from ruby 1.6 to ruby 1.8 and 
> updated all of its libraries to their latest versions (it uses dbi and 
> dbd-postgres).  The problem i am having now is that it appears to start 
> out using a sane amount of memory (around 8mb) but then by the next day 
> around the same time will be using close to 200MB for the ruby 
> interpreter alone.  The daemon code itself is 100% ruby so I don't 
> understand how this leak is happening.  Are there any dangerous code 
> segments I should look for that could make it do this?  The only thing I 
> could think of is the fact that every returned object from a sql query 
> is .dup'd since ruby dbi passes a reference. However, these should be 
> getting swept up automatically by the garbage collector.  This is 
> driving me nuts and I would love it if someone could point me in the 
> right direction..

If the 200MB is used by objects that are still known to the interpreter 
(i.e., not garbage), then you can use ObjectSpace to find them. For 
instance, just to count objects of each class:

irb(main):001:0> h = Hash.new(0); ObjectSpace.each_object {|x| 
h[x.class] += 1}
=> 6287
irb(main):002:0> h
=> {RubyToken::TkRBRACE=>1, IO=>3, Regexp=>253, IRB::WorkSpace=>1, 
SLex::Node=>78, RubyToken::TkRBRACK=>1, RubyToken::TkINTEGER=>2, 
Float=>5, NoMemoryError=>1, SLex=>1, RubyToken::TkRPAREN=>1, 
RubyToken::TkBITOR=>2, RubyToken::TkIDENTIFIER=>7, RubyToken::TkNL=>1, 
RubyToken::TkCONSTANT=>2, Proc=>49, IRB::Context=>1, IRB::Locale=>1, 
RubyToken::TkSPACE=>7, ThreadGroup=>1, RubyToken::TkLPAREN=>1, 
Thread=>1, fatal=>1, File=>10, String=>4413, Data=>1, 
RubyToken::TkfLBRACE=>1, RubyToken::TkDOT=>3, 
IRB::ReadlineInputMethod=>1, RubyToken::TkASSIGN=>1, Hash=>136, 
IRB::Irb=>1, RubyToken::TkfLBRACK=>1, Object=>6, RubyLex=>1, 
RubyToken::TkSEMICOLON=>1, MatchData=>111, Tempfile=>1, Module=>23, 
RubyToken::TkOPASGN=>1, SystemStackError=>1, Binding=>2, Class=>345, 
Array=>806}