Re: [AD] Allegro in a multithreaded way

[aj <aj@xxxxxxxxxx>]

At 12:31 PM 13/01/2005, you wrote:
> I am making a game called Paintown for which you can download a demo, 
> http://www.ccs.neu.edu/~workmin/paintown.zip. Binary for windows. Anyway 
> I, as well as other people, have experienced a crash when the loading 
> begins becuase I am spawning two threads when the game starts. In one 
> thread I show a title screen and some colored letters while in the other 
> thread I load all the data. I know that Allegro is not multithread-safe 
> but I figured as long as I dont touch the screen in the thread that loads 
> everything I should be ok. Am I mistaken about this? The crash only occurs 
> on windows, I never experience any problems in Linux where it was developed.
>
> I am using the pthreads for windows library from 
> http://sources.redhat.com/pthreads-win32/. I have tried to debug the 
> program, but the crash occurs in random places at random times so I can 
> only assume the bug is memory related or something of that nature. 
> Actually the game doesnt crash, per se, it just receives SIGTRAP such that 
> when the program is not run in a debugger with nothing to catch the signal 
> the program just crashes. If I run the program in gdb and continue past 
> these signals then it works fine. Also if I dont spawn the thread that 
> shows the title screen it works fine.
>
> Kind of an incoherent email, but does anyone know that Allegro cannot be 
> used in a multithreaded way or if pthreads is just a bad library to use on 
> windows? Any other suggestions are welcome.



i use allegro, pthreads, and windows threads at the same time.   so its OK 
to be using pthreads.
allegro has many global variables, that can not be accessed by multiple 
threads.
i "suggest" that you create a global lock/mutex thingy  that locks any use 
of allegro functions.
note:  i only  *suggest* this approach, its not a nice way, but its the 
only way i can see it working.