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Multithreading Related Problems
Elias
Member #358
May 2000

From what I've read the point of 100Hz or 120Hz monitors is different... a large amount of movies uses 24 FPS. On a 60Hz monitor that can't be smoothly displayed without stutter since not each frame can be displayed for the same time (unless you do some kind of interpolation - which leads to different artifacts). On 100 Hz or 120 Hz it looks completely smooth however (each single source frame is displayed for 4 or 5 frames respectively).

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"Either help out or stop whining" - Evert

RPG Hacker
Member #12,492
January 2011
avatar

Yeah, I reduced the timer to 100 FPS now. Seems to be the best solution. Anything above is overkill, really.

J-Gamer said:

If the render thread has an event queue that listens to a user event source from the logic thread, you can send events from the logic thread to the render thread trough al_emit_user_event. The queue in the render thread will automatically get the event.

That is exactly what I intend to do. Don't know if I made another impression. All I need to know is if event queues are thread-safe (in other words: if one thread can edit/fill an event queue while another is reading it) or if I need to protect them from simultaneous access. Of course I could read AND clear the event queue in the rendering thread, but in my opinion that's inconvenient, so as long as it's not unsafe I prefer to clear the event queue in the logic thread. Or in other words: Whenver the logic threads emits a new user event, I want it to clear the last one afterwards (probably with al_get_next_event(), whereas I use al_peek_next_event() in the rendering thread).

Elias
Member #358
May 2000

Event queues are thread safe.

--
"Either help out or stop whining" - Evert

RPG Hacker
Member #12,492
January 2011
avatar

Alright, thanks. That's all for now.

Audric
Member #907
January 2001

Even if the allegro functions are thread safe, the way you describe isn't. You can't have two threads read the same queue, each at their own speed.

RPG Hacker
Member #12,492
January 2011
avatar

I'll always make sure that the rendering thread has at least one valid event to work with (since I'll use al_peek_next_event()), so as long as simultaneously reading/editing the queue itself doesn't cause errors I'll be fine.

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