From: s.wanabe@...
Date: 2017-08-01T01:07:24+00:00
Subject: [ruby-core:82220] [Ruby trunk Bug#13775] Ruby hangs when calling scope and belongs_to many times (with mongomapper)

Issue #13775 has been updated by wanabe (_ wanabe).


mtsmfm (Fumiaki Matsushima) wrote:
> Oops!
> Sorry, I committed and pushed!

Thank you. reproduced.

I guess this is a GC issue.
Here is a reproducible code with cflags="-DRGENGC_CHECK_MODE=2" build.
this code works fine (= no [BUG]) without RGENGC_CHECK_MODE.

```
b = proc { }
10.times do |i|
  p i
  b.clone
  GC.start
end
```

I saw below output.

```
0
1
b.rb:5: [BUG] inconsistent old slot nubmer: expect 2916, but 2917.
ruby 2.5.0dev (2017-07-31 trunk 59454) [x86_64-linux]
(snip)
```

And `git bisect` shows that this is from r55766 [Feature #12628].

----------------------------------------
Bug #13775: Ruby hangs when calling scope and belongs_to many times (with mongomapper)
https://bugs.ruby-lang.org/issues/13775#change-65987

* Author: mtsmfm (Fumiaki Matsushima)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.4.1
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
Following code will hang Ruby:

~~~ruby
require 'bundler/setup'
require 'mongo_mapper'
MongoMapper.setup(
  {
    'development' => {
      'host' => 'mongo', 'port' => 27017, 'database' => 'db'
    }
  },
  'development'
)

class A
  include MongoMapper::Document

  10000.times do |i|
    scope :"scope_#{i}", order(:"order_#{i}")
    belongs_to :"col_#{i}"
  end
end
~~~

I confirmed that it will happen 2.4.1 and trunk (ruby 2.5.0dev (2017-07-18 trunk 59362) [x86_64-linux]).

Backtrace:

~~~
/vendor/bundle/gems/mongo_mapper-0.14.0/lib/mongo_mapper/plugins/associations/single_association.rb:8: [BUG] rb_gc_mark(): 0x0000000178d240 is T_NONE
ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0015 p:---- s:0062 e:000061 CFUNC  :module_eval
c:0014 p:0125 s:0057 e:000056 METHOD /vendor/bundle/gems/mongo_mapper-0.14.0/lib/mongo_mapper/plugins/associations/single_association.rb:8
c:0013 p:0078 s:0052 e:000051 METHOD /vendor/bundle/gems/mongo_mapper-0.14.0/lib/mongo_mapper/plugins/associations/belongs_to_association.rb:21
c:0012 p:0033 s:0047 e:000046 METHOD /vendor/bundle/gems/mongo_mapper-0.14.0/lib/mongo_mapper/plugins/associations.rb:64
c:0011 p:0029 s:0042 e:000041 METHOD /vendor/bundle/gems/mongo_mapper-0.14.0/lib/mongo_mapper/plugins/associations.rb:14
c:0010 p:0013 s:0035 e:000034 BLOCK  main.rb:29 [FINISH]
c:0009 p:---- s:0031 e:000030 IFUNC
c:0008 p:---- s:0028 e:000027 CFUNC  :upto
c:0007 p:---- s:0025 e:000024 CFUNC  :each
c:0006 p:0018 s:0021 e:000020 METHOD /vendor/bundle/gems/activesupport-4.2.9/lib/active_support/core_ext/range/each.rb:7
c:0005 p:0037 s:0016 E:0007e0 CLASS  main.rb:28
c:0004 p:0011 s:0013 e:000012 BLOCK  main.rb:23 [FINISH]
c:0003 p:---- s:0010 e:000009 CFUNC  :times
c:0002 p:0068 s:0006 e:000005 EVAL   main.rb:22 [FINISH]
c:0001 p:0000 s:0003 E:001b80 (none) [FINISH]
~~~

Steps to reproduce:

~~~
git clone https://gist.github.com/dbbf1afabd372aa1269a954911292cfe.git
cd dbbf1afabd372aa1269a954911292cfe
docker-compose run ruby-2-4-1
docker-compose run ruby-trunk
~~~

Full backtrace in my gist.
https://gist.github.com/mtsmfm/dbbf1afabd372aa1269a954911292cfe



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