# What appears to be a really sneaky bug related to loading assemblies (System::Action is temporarily

**URL:** <https://www.ruby-forum.com/t/what-appears-to-be-a-really-sneaky-bug-related-to-loading-assemblies-system-action-is-temporarily/184952>\
**Category:** IronRuby\
**Created:** [March 10, 2010, 9:58pm UTC](https://www.ruby-forum.com/t/what-appears-to-be-a-really-sneaky-bug-related-to-loading-assemblies-system-action-is-temporarily/184952 "2010-03-10T21:58:02Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Orion\_E](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/65b543/32.png) [@Orion\_E](https://www.ruby-forum.com/u/Orion_E)\
**Post date:** [March 10, 2010, 9:58pm UTC](https://www.ruby-forum.com/t/what-appears-to-be-a-really-sneaky-bug-related-to-loading-assemblies-system-action-is-temporarily/184952/1 "2010-03-10T21:58:02Z")

</div>

Intro: Using IronRuby 1.0 rc2; .NET 3.5SP1 on windows XP sp3  
I have some code which is using DynamicMethod / GetILGenerator to create  
statically typed methods at runtime, so I can call IUnknown-based COM  
objects from IronRuby.

Here is a snippet

# … piles of code which figures out what the method signature should

be  
and generates it …  
func\_type\_params = [System::Object] + someotherstuff

# generate a .NET delegate to wrap the new DynamicMethod

puts “DEBUG: Action= #{System::Action.inspect}”  
puts “DEBUG: Params= #{func\_type\_params.inspect}”  
puts “DEBUG: F= #{System::Action.of(\*func\_type\_params)}”  
del\_type = System::Action.of(\*func\_type\_params).to\_clr\_type

This has been working reliably for some time, and still works with most  
input. However, we’ve recently seen random failures. Here’s some of the  
output from those Debug lines:

# successful

DEBUG: Action= #\<TypeGroup: System::Action, System::Action[T],  
System::Action[T1, T2], System::Action[T1, T2, T3], System::Action[T1,  
T2,  
T3, T4]\>  
DEBUG: Params= [Object, Object, Object]  
DEBUG: F= System::Action[Object, Object, Object]

# and then the next one fails

DEBUG: Action= nil  
DEBUG: Params= [Object, Fixnum, Interop::FieldID[], System::Object[]]  
NoMethodError: undefined method `of’ for NilClass

As far as that tells me, System::Action has somehow been set to nil.  
Note: The point at which System::Action gets nil’ed out is NOT always  
the  
same point.

If I run the code under iirb (copy/pasting my original script in), and  
then  
after the exception inspect System::Action, it reports this:

=\> #\<TypeGroup: System::Action, System::Action[T], System::Action[T1,  
T2],  
System::Action[T1, T2, T3], System::Action[T1, T2, T3, T4],  
System::Action[T1, T2, T3, T4, T5], System::Action[T1, T2, T3, T4, T5,  
T6],  
System::Action[T1, T2, T3, T4, T5, T6,  
T7], System::Action[T1, T2, T3, T4, T5, T6, T7, T8], System::Action[T1,  
T2,  
T3, T4, T5, T6, T7, T8, T9], System::Action[T1, T2, T3, T4, T5, T6, T7,  
T8,  
T9, T10], System::Action[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11],  
System::Action[T1, T2, T3,  
T4, T5, T6, T7, T8, T9, T10, T11, T12], System::Action[T1, T2, T3, T4,  
T5,  
T6, T7, T8, T9, T10, T11, T12, T13], System::Action[T1, T2, T3, T4, T5,  
T6,  
T7, T8, T9, T10, T11, T12, T13, T14], System::Action[T1, T2, T3, T4, T5,  
T6,  
T7, T8, T9, T10, T11,  
T12, T13, T14, T15], System::Action[T1, T2, T3, T4, T5, T6, T7, T8, T9,  
T10, T11, T12, T13, T14, T15, T16]\>

As you can see, System::Action is no longer nil, but has now been given  
a  
bunch more overloads. These overloads come from System.CoreEx (part of  
the  
.NET reactive framework). Putting require ‘System.CoreEx’ at the top of  
my  
script to pre-load it makes this error go away.

> From what I can tell, something causes the CLR to on-demand load  
> System.CoreEx.dll. This in turn adds more overloads to System::Action.  
> IronRuby appears to temporarily nil it out while loading, thus causing  
> the  
> crash.

Am I on the right track? As mentioned I think I can work around it by  
preloading all the dll’s I know I’m going to need, but this doesn’t seem  
to  
be a reliable long-term solution.

Cheers, Orion

---

<div class="post-metadata">

**Author:** ![Orion\_E](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/65b543/32.png) [@Orion\_E](https://www.ruby-forum.com/u/Orion_E)\
**Post date:** [March 10, 2010, 11:38pm UTC](https://www.ruby-forum.com/t/what-appears-to-be-a-really-sneaky-bug-related-to-loading-assemblies-system-action-is-temporarily/184952/2 "2010-03-10T23:38:07Z")

</div>

Could you try to write a simple repro in a .rb file that demonstrates  
the issue?

Tomas

From: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
[[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] On Behalf Of Orion E.  
Sent: Wednesday, March 10, 2010 12:42 PM  
To: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
Subject: [Ironruby-core] What appears to be a really sneaky bug related  
to loading assemblies (System::Action is temporarily nil)

Intro: Using IronRuby 1.0 rc2; .NET 3.5SP1 on windows XP sp3  
I have some code which is using DynamicMethod / GetILGenerator to create  
statically typed methods at runtime, so I can call IUnknown-based COM  
objects from IronRuby.

Here is a snippet

# … piles of code which figures out what the method signature should

be and generates it …  
func\_type\_params = [System::Object] + someotherstuff

# generate a .NET delegate to wrap the new DynamicMethod

puts “DEBUG: Action= #{System::Action.inspect}”  
puts “DEBUG: Params= #{func\_type\_params.inspect}”  
puts “DEBUG: F= #{System::Action.of(\*func\_type\_params)}”  
del\_type = System::Action.of(\*func\_type\_params).to\_clr\_type

This has been working reliably for some time, and still works with most  
input. However, we’ve recently seen random failures. Here’s some of the  
output from those Debug lines:

# successful

DEBUG: Action= #\<TypeGroup: System::Action, System::Action[T],  
System::Action[T1, T2], System::Action[T1, T2, T3], System::Action[T1,  
T2, T3, T4]\>  
DEBUG: Params= [Object, Object, Object]  
DEBUG: F= System::Action[Object, Object, Object]

# and then the next one fails

DEBUG: Action= nil  
DEBUG: Params= [Object, Fixnum, Interop::FieldID, System::Object]  
NoMethodError: undefined method `of’ for NilClass

As far as that tells me, System::Action has somehow been set to nil.  
Note: The point at which System::Action gets nil’ed out is NOT always  
the same point.

If I run the code under iirb (copy/pasting my original script in), and  
then after the exception inspect System::Action, it reports this:

=\> #\<TypeGroup: System::Action, System::Action[T], System::Action[T1,  
T2], System::Action[T1, T2, T3], System::Action[T1, T2, T3, T4],  
System::Action[T1, T2, T3, T4, T5], System::Action[T1, T2, T3, T4, T5,  
T6], System::Action[T1, T2, T3, T4, T5, T6,  
T7], System::Action[T1, T2, T3, T4, T5, T6, T7, T8], System::Action[T1,  
T2, T3, T4, T5, T6, T7, T8, T9], System::Action[T1, T2, T3, T4, T5, T6,  
T7, T8, T9, T10], System::Action[T1, T2, T3, T4, T5, T6, T7, T8, T9,  
T10, T11], System::Action[T1, T2, T3,  
T4, T5, T6, T7, T8, T9, T10, T11, T12], System::Action[T1, T2, T3, T4,  
T5, T6, T7, T8, T9, T10, T11, T12, T13], System::Action[T1, T2, T3, T4,  
T5, T6, T7, T8, T9, T10, T11, T12, T13, T14], System::Action[T1, T2, T3,  
T4, T5, T6, T7, T8, T9, T10, T11,  
T12, T13, T14, T15], System::Action[T1, T2, T3, T4, T5, T6, T7, T8, T9,  
T10, T11, T12, T13, T14, T15, T16]\>

As you can see, System::Action is no longer nil, but has now been given  
a bunch more overloads. These overloads come from System.CoreEx (part of  
the .NET reactive framework). Putting require ‘System.CoreEx’ at the top  
of my script to pre-load it makes this error go away.

> From what I can tell, something causes the CLR to on-demand load System.CoreEx.dll. This in turn adds more overloads to System::Action.  
> IronRuby appears to temporarily nil it out while loading, thus causing  
> the crash.

Am I on the right track? As mentioned I think I can work around it by  
preloading all the dll’s I know I’m going to need, but this doesn’t seem  
to be a reliable long-term solution.

Cheers, Orion