Memleak with GL context

#1

Hi! I am programming multithread rendering with opengl. I create 2 new threads and a new context for each.

Memory rises on SDL_GL_MakeCurrent(window, xContext) call.


SDL_GLContext mainContext = nullptr;
SDL_GLContext simulationThreadContext = nullptr;
SDL_GLContext renderThreadContext = nullptr;

SDL_Window* window = nullptr;

SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 6);
SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
window = SDL_CreateWindow("window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1600, 900, SDL_WINDOW_OPENGL);

simulationThreadContext = SDL_GL_CreateContext(window);
renderThreadContext = SDL_GL_CreateContext(window);
mainContext = SDL_GL_CreateContext(window);

//glew things
InitOpengl();

std::thread simulationThread;
std::thread renderThread;

while (!quit)
{
	while (SDL_PollEvent(&event)) {
		if (event.type == SDL_QUIT) {
			quit = true;
		}
	}

	taskQueue.clear();

	simulationThread = std::thread([&]() {
		SDL_GL_MakeCurrent(window, simulationThreadContext);

		//UpdateSim();
		//simDone.store(true);

		SDL_GL_MakeCurrent(window, nullptr);
	});	

	renderThread = std::thread([&]() {
		SDL_GL_MakeCurrent(window, renderThreadContext);

                //while (!(taskQueue.empty() && simDone.load())) {
		//	RenderSim();
		//}

		SDL_GL_MakeCurrent(window, nullptr);
	});

		simulationThread.join();
		renderThread.join();

	SDL_GL_MakeCurrent(window, mainContext);
	SDL_GL_SwapWindow(window);
	SDL_GL_MakeCurrent(window, nullptr);
}

SDL_GL_DeleteContext(simulationThreadContext);
SDL_GL_DeleteContext(renderThreadContext);
SDL_GL_DeleteContext(mainContext);

SDL_DestroyWindow(window);

I commented out task queue part that is responsible for adding work and doing it, to be sure that it is not problem with this and memleak still occurs.

Problem with memory fixes when SDL_GL_MakeCurrent() is commented.

Is there a problem on my side?

#2

I do not see anything in the documentation of SDL_GL_MakeCurrent() which indicates that it is legitimate to pass NULL as the context:

SDL_GL_MakeCurrent(window, nullptr);

Might that be the problem?

#3

SDL_GL_MakeCurrent(window, nullptr);
Might that be the problem?

Nope, it can be commented out and still got the memleak. Does not really matter.