Polling for events drastically lowers frame rate

[Ltp0wer]

I am having a strange problem.

Anytime I am polling for events, my frame rate drops incredibly. Even more so if I am moving the mouse while polling for events.

For example, with this code:

Code: [Select]


#include <SFML/Graphics.hpp>


int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 800), "SFML window");


    while (window.IsOpened())
    {
        window.Clear();


        /*
        sf::Event event;
        while (window.PollEvent(event))
        {
            if (event.Type == sf::Event::Closed)
                window.Close();

            if (event.Type == sf::Event::KeyPressed)
            {
                if (event.Key.Code == sf::Keyboard::Key::Escape)
                    window.Close();
            }
        }
        */

        window.Display();
    }

    return EXIT_SUCCESS;

I get well over 1000 FPS with this code. When I uncomment the block polling for events, I get around 50 fps, and if I move my mouse around the window (slowly or quickly), it drops to a range of 1-20.

My specs are:
Q6600 Intel Core2Quad 2.66ghz
Nvidia GeForce GTX 260
3.5GB of RAM

I am using SFML 2.0

I don't think this is an SFML problem, as old programs I made in SFML 1.6 on a different computer, run slow as well on this computer. Also, my friend who also uses SFML 2.0, sent me a program he made that just displays the FPS in the graphics window. As I expected, I get the same low fps problem.

Are there any known issues that would cause this? I've already tried updating my graphics card drivers, and it hasn't helped.

Thanks.

Edit:

Operating system is Windows 7 32bit

Also, I have tried compiling my programs in both debug and release mode, as well as both dynamic linking and static linking, and I have the same issue.

[OniLinkPlus]

That... is weird. It doesn't even sound like a driver issue. It sounds more like your computer is on the verge of imploding. Do you have anti-virus installed? What operating system?

[Ltp0wer]

That... is weird. It doesn't even sound like a driver issue. It sounds more like your computer is on the verge of imploding. Do you have anti-virus installed? What operating system?

No anti-virus, but I run Spybot S&D and Ad-aware SE Personal every once in awhile. I'll try doing that now.

Operating system is Windows 7 32bit (Can't believe I forgot to include that in the OP)

Also, I should mention that this doesn't happen with any other games I have played, but then again, most of those are Direct3D AAA titles.

[Laurent]

Can you try to comment the call to ProcessJoystickEvents in src/SFML/Window/Window.cpp?

[Ltp0wer]

Can you try to comment the call to ProcessJoystickEvents in src/SFML/Window/Window.cpp?

I commented out "ProcessJoystickEvents();" on line 121 and line 133 of src/SFML/Window/WindowImpl.cpp and recompiled.

It is working beautifully.

You are a god damn genius.

What does this mean though?

[Laurent]

Each time this function is called, it polls joysticks to see if they are connected/disconnected. Apparently this is a very slow operation.

Unfortunately, on Windows there's no asynchronous/callback system that would notify when a joystick is connected/disconnected, which would avoid this polling and save a lot of CPU. I still need to find a solution to this -- maybe just increase the polling interval.

[slotdev]

Can you try to comment the call to ProcessJoystickEvents in src/SFML/Window/Window.cpp?

Laurent is this an issue that anyone who doesnt use a joystick should also comment out from the code?

[Laurent]

Laurent is this an issue that anyone who doesnt use a joystick should also comment out from the code?

Until it's fixed, yes, it is a potential problem.

[Nexus]

Is this function only needed to recognize the plugging-in of a joystick while SFML is running or does it poll the actual joystick events? In the first case, SFML could do it at startup and provide a function in sf::Joystick to call manually later. It's not beautiful however, and I would only do it if the automatic recognition is a severe performance issue.

By the way, are the IsConnected() and Update() functions of sf::Joystick somehow related to this?

[Laurent]

In fact the guilty one is JoystickImpl::IsConnected, which is called by JoystickManager::Update, which is called by WindowImpl::ProcessJoystickEvents.

A simple workaround would be to call JoystickManager::Update only once per second (for example) instead of everytime PollEvent is called.

[mbro2k]

Hey I tried Laurent's suggestion and only called IsConnected every few seconds and it solved my problem!
(my problem was a choppy framerate when running with a newly connected xbox controller for the first time).

Actually I had to keep JoystickManager::Update running normally, because my joystick would not work properly.
I actually put the timer before the IsConnected function itself within
JoystickManager::Update

[Laurent]

Yes, that was the right thing to do, my previous message was incorrect

[Tex Killer]

Wouldn't it be possible to run that method on a separate thread, and every frame just check if the thread had finished, re-launching it if it had?

[Felheart]

I think a seperate thread would be acceptable untill there is a better solution.
In my game I need those functions (the easy access to gamepads / joysticks is one of the reasons I switched to SFML).
If you increase the polling intervall, wouldn't the input-delay rise with it?
That would be horrible

[Tex Killer]

If it have a delay high enough to damage FPS, then it will be always bad to put it in the same thread as the game loop. If it is in a separate thread, it will not damage FPS and will be called right when it is ready to be called, without waiting for seconds or so.