Issue #9205 has been updated by nagachika (Tomoyuki Chikanaga). Backport changed from 1.9.3: UNKNOWN, 2.0.0: REQUIRED to 1.9.3: UNKNOWN, 2.0.0: DONE r43994 was backported to ruby_2_0_0 at r44319. ---------------------------------------- Bug #9205: Assertion failed: heap_pages_deferred_final == 0 https://bugs.ruby-lang.org/issues/9205#change-43798 Author: phasis68 (Heesob Park) Status: Closed Priority: Normal Assignee: Category: Target version: ruby -v: ruby 2.1.0dev (2013-12-02 trunk 43958) [x64-mswin64_120] Backport: 1.9.3: UNKNOWN, 2.0.0: DONE If I run the following code: raise_proc = proc do |id| p "Finalizer one on #{id}" end 10000.times do ObjectSpace.define_finalizer(Object.new, raise_proc) end I can see an assertion failure. "Finalizer one on 24535120" Assertion failed: heap_pages_deferred_final == 0, file gc.c, line 2111 Same error with ruby 2.0.0p353 (2013-11-22) [i386-mingw32] -- http://bugs.ruby-lang.org/