[Ironruby-core] Problems with Mutex and ConditionVariable under IronRuby

Daniele Alessandri suppakilla at gmail.com
Fri Jan 2 07:35:15 EST 2009


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/


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