From: Hongli Lai <hongli@...99.net>
Date: 2008-03-04T19:20:11+09:00
Subject: Re: embedding Ruby 1.9.0 inside pthread

Suraj N. Kurapati wrote:
> I moved the ruby initialization calls to the main thread as you
> suggested and the example worked!  The revised main.c is now:

You also seem to be using locks in a wrong way. In main() you have:

 >       pthread_mutex_init(&gCProgLock, NULL);
 >       pthread_mutex_lock(&gCProgLock);
 >
 >       pthread_create(&gRubyThread, NULL, gRubyThread_body, NULL);
 >       pthread_mutex_lock(&gCProgLock); // C program blocks here

And in the thread you have:

 >       pthread_mutex_unlock(&gCProgLock);

You are unlocking a mutex, which was locked by another thread. This is a 
violation of the POSIX API. I quote the man page:

"!pthread_mutex_unlock! unlocks the given mutex. The mutex is assumed to 
be  locked  and  owned  by  the   calling   thread   on   entrance   to 
!pthread_mutex_unlock!."

If you want to wake up the main thread (which was sleeping on some kind 
of condition) then you should use conditioned variables instead.