Ironruby core - Jan 2009 - Problems with Mutex and ConditionVariable under IronRuby

Hello,

I was playing with threads under IronRuby but it seems like I have
stumbled on problems with Mutex and ConditionVariable. At first I
thought the problem was related to my code even if it actually worked
flawlessy for months under MRI 1.8.6 and it runs fine under the latest
JRuby, so I tried to run the most basic example of using these two
classes (a classic one:
http://www.rubycentral.com/pickaxe/tut_threads.html#UF) but the
problems still persist.

At first I thought it was some kind of deadlock given that the output
obtained by running the code with ir.exe is as follows:

C:\Sviluppo\ironruby\SVN\trunk\build\debug>ir T002.rb
A: I have critical section, but will wait for cv
(Later, back at the ranch...)
B: Now I am critical, but am done with cv

(note that the process remains stuck there)

So I went debugging with Visual Studio and this is what I got in the
output window:
http://gist.github.com/raw/42514/8d38b629e8ae62d9c4bece398a4041b036d28f12

To make it short, the reported exception is thrown when the ruby code
calls ConditionVariable#signal and IronRuby internally calls
Monitor.Pulse on the Mutex instance:

[RubyMethod("signal")]
public static RubyConditionVariable/*!*/
Signal(RubyConditionVariable/*!*/ self) {
    RubyMutex m = self._mutex;
    if (m != null) {
        Monitor.Pulse(m);
    }
    return self;
}

It seems like the Monitor is not aware of being in a synchronized
block of code (or is not in a critical section at all). Any clues?

Thanks,

Daniele

-- 
Daniele Alessandri
http://www.clorophilla.net/blog/

It looks like ConditionVariable.wait isn''t implemented in a way
that''s consistent with the spec. Please file a bug report on RubyForge.

I''m a bit surprised by the semantics of this class.  It
doesn''t appear possible to use it safely unless there''s at
least one additional level of locking.

-----Original Message-----
From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core-bounces at
rubyforge.org] On Behalf Of Daniele Alessandri
Sent: Friday, January 02, 2009 4:35 AM
To: ironruby-core at rubyforge.org
Subject: [Ironruby-core] Problems with Mutex and ConditionVariable under
IronRuby

Hello,

I was playing with threads under IronRuby but it seems like I have
stumbled on problems with Mutex and ConditionVariable. At first I
thought the problem was related to my code even if it actually worked
flawlessy for months under MRI 1.8.6 and it runs fine under the latest
JRuby, so I tried to run the most basic example of using these two
classes (a classic one:
http://www.rubycentral.com/pickaxe/tut_threads.html#UF) but the
problems still persist.

At first I thought it was some kind of deadlock given that the output
obtained by running the code with ir.exe is as follows:

C:\Sviluppo\ironruby\SVN\trunk\build\debug>ir T002.rb
A: I have critical section, but will wait for cv
(Later, back at the ranch...)
B: Now I am critical, but am done with cv

(note that the process remains stuck there)

So I went debugging with Visual Studio and this is what I got in the
output window:
http://gist.github.com/raw/42514/8d38b629e8ae62d9c4bece398a4041b036d28f12

To make it short, the reported exception is thrown when the ruby code
calls ConditionVariable#signal and IronRuby internally calls
Monitor.Pulse on the Mutex instance:

[RubyMethod("signal")]
public static RubyConditionVariable/*!*/
Signal(RubyConditionVariable/*!*/ self) {
    RubyMutex m = self._mutex;
    if (m != null) {
        Monitor.Pulse(m);
    }
    return self;
}

It seems like the Monitor is not aware of being in a synchronized
block of code (or is not in a critical section at all). Any clues?

Thanks,

Daniele

--
Daniele Alessandri
http://www.clorophilla.net/blog/
_______________________________________________
Ironruby-core mailing list
Ironruby-core at rubyforge.org
http://rubyforge.org/mailman/listinfo/ironruby-core

On Fri, Jan 2, 2009 at 17:56, Curt Hagenlocher <curth at microsoft.com>
wrote:
> It looks like ConditionVariable.wait isn''t implemented in a way
that''s consistent with the spec. Please file a bug report on RubyForge.
Bug report filed.

While I was at it, I filed another bug report about potential
multithreading issues when modules are initialized by IronRuby. See:
http://rubyforge.org/tracker/index.php?func=detail&aid=23408&group_id=4359&atid=16798

-- 
Daniele Alessandri
http://www.clorophilla.net/blog/

Thanks for a very detailed bug report!

-----Original Message-----
From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core-bounces at
rubyforge.org] On Behalf Of Daniele Alessandri
Sent: Friday, January 02, 2009 11:40 AM
To: ironruby-core at rubyforge.org
Subject: Re: [Ironruby-core] Problems with Mutex and ConditionVariable under
IronRuby

On Fri, Jan 2, 2009 at 17:56, Curt Hagenlocher <curth at microsoft.com>
wrote:
> It looks like ConditionVariable.wait isn''t implemented in a way
that''s consistent with the spec. Please file a bug report on RubyForge.
Bug report filed.

While I was at it, I filed another bug report about potential
multithreading issues when modules are initialized by IronRuby. See:
http://rubyforge.org/tracker/index.php?func=detail&aid=23408&group_id=4359&atid=16798

-- 
Daniele Alessandri
http://www.clorophilla.net/blog/
_______________________________________________
Ironruby-core mailing list
Ironruby-core at rubyforge.org
http://rubyforge.org/mailman/listinfo/ironruby-core

On Fri, Jan 2, 2009 at 21:03, Curt Hagenlocher <curth at microsoft.com>
wrote:
> Thanks for a very detailed bug report!
I just filed another bug :-)

"A Fixnum fails to grow to a Bignum when using the left shift
operator"
http://rubyforge.org/tracker/index.php?func=detail&aid=23414&group_id=4359&atid=16798

I tackled this bug when I noticed strange behaviours/errors under
IronRuby while using ruby''s IPAddr class.

-- 
Daniele Alessandri
http://www.clorophilla.net/blog/