From: Robert Pankowecki <robert.pankowecki@...>
Date: 2011-10-12T22:06:45+09:00
Subject: [ruby-core:40117] [Ruby 1.9 - Bug #5437][Open] Using fibers leads to huge memory leak


Issue #5437 has been reported by Robert Pankowecki.

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Bug #5437: Using fibers leads to huge memory leak
http://redmine.ruby-lang.org/issues/5437

Author: Robert Pankowecki
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 1.9.3dev (2011-10-11 revision 33457) [x86_64-linux]


It appears to me that there is something wrong with reallocating (reusing?) memory used by fibers. Here is a little script:

<code>
require 'fiber'

fibers = 10_000.times.map do
  Fiber.new do
    f = Fiber.current
    Fiber.yield
  end
end; nil

fibers.each(&:resume); nil
fibers.each(&:resume); nil
fibers = []

GC.start
</code>

Running this code in IRB multiple times leads to consuming more and more memory every time. However every time I execute this code the amount of newly consumed memory is lower. I was able to repeat this bug with ruby 1.9.2.p290 and 1.9.3-head using 32 and 64 bit architecture.

Here are some memory stats:
a) 32bit
Iter | VSZ | RSS
1 186268 63508
2 360196 119580
3 360340 147600
4 360484 178552
5 360616 199968
6 360612 210716
7 360612 221920
8 360612 224544
9 360612 229976

b) 64bit
1 395152 107600
2 739924 176532
3 739924 187972
4 739924 203300
5 739924 217716
6 739924 218344
7 739924 218540
8 739924 234040
9 739924 234256

We can see on our production instance that the more Fibers are in use the more memory is never reclaimed back to OS and the bigger the leak is.


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