Drawing from a render target on master causes a memory leak

[JaniM]

The following code snippet leaks memory on each iteration, very quickly exhausting all system memory.

Tested on MacOS on 0.4.13 and master. This does NOT happen on 0.4.13, ie. this is a regression.

use macroquad::prelude::*;

const VIRTUAL_WIDTH: f32 = 1280.0;
const VIRTUAL_HEIGHT: f32 = 720.0;

#[macroquad::main("Letterbox")]
async fn main() {
    loop {
        let render_target = render_target(VIRTUAL_WIDTH as u32, VIRTUAL_HEIGHT as u32);

        let mut render_target_cam =
            Camera2D::from_display_rect(Rect::new(0., 0., VIRTUAL_WIDTH, VIRTUAL_HEIGHT));
        render_target_cam.render_target = Some(render_target.clone());

        // Deleting the draw removes the memory leak
        draw_texture_ex(
            &render_target.texture,
            0.0,
            0.0,
            WHITE,
            DrawTextureParams {
                dest_size: Some(vec2(VIRTUAL_WIDTH, VIRTUAL_HEIGHT)),
                ..Default::default()
            },
        );

        next_frame().await;
    }
}

[KurlykovDanila]

Are you sure the problem is in the method draw_texture_ex?
I removed it and the memory leak remained. The leak is clearly in this block of code, because if you take it out of the loop, the problem will disappear.

let render_target = render_target(VIRTUAL_WIDTH as u32, VIRTUAL_HEIGHT as u32);
let mut render_target_cam = Camera2D::from_display_rect(Rect::new(0., 0., VIRTUAL_WIDTH, VIRTUAL_HEIGHT));
render_target_cam.render_target = Some(render_target.clone());

This code has no problems:

use macroquad::prelude::*;

const VIRTUAL_WIDTH: f32 = 1280.0;
const VIRTUAL_HEIGHT: f32 = 720.0;

#[macroquad::main("Letterbox")]
async fn main() {
    let render_target = render_target(VIRTUAL_WIDTH as u32, VIRTUAL_HEIGHT as u32);
    let mut render_target_cam = Camera2D::from_display_rect(Rect::new(0., 0., VIRTUAL_WIDTH, VIRTUAL_HEIGHT));
    render_target_cam.render_target = Some(render_target.clone());

    loop {
        draw_texture_ex(
            &render_target.texture,
            0.0,
            0.0,
            WHITE,
            DrawTextureParams {
                dest_size: Some(vec2(VIRTUAL_WIDTH, VIRTUAL_HEIGHT)),
                ..Default::default()
            },
        );

        next_frame().await;
    }
}

[JaniM]

I am sure, on my machine it does not leak without the draw. Ie. something about drawing the texture prevents the texture from being dropped. The reason your snippet doesn't exhibit a leak is that we never drop and create a new texture.

[KurlykovDanila]

Interesting, because on my machine this function causes a memory leak:

use macroquad::prelude::*;

#[macroquad::main("Letterbox")]
async fn main() {
    loop {
        let render_target = render_target(1280, 720);

        next_frame().await;
    }
}

[JaniM]

I just noticed I forgot to remove the camera from the reproduction, it is irrelevant.

Interesting, because on my machine this function causes a memory leak:

Oh huh, this does leak for me too, but very slowly. With the draw (below), it blows a GB in a couple seconds. Without, it takes several minutes.

use macroquad::prelude::*;

#[macroquad::main("Letterbox")]
async fn main() {
    loop {
        let render_target = render_target(1280, 720);

        draw_texture_ex(&render_target.texture, 0.0, 0.0, WHITE, Default::default());

        next_frame().await;
    }
}

[JaniM]

Hmm. It seems to be a difference in virtual and real memory. Both versions grow in real memory at the same rate, but the draw version blows through virtual memory.

With draw:

Without draw:

[KurlykovDanila]

https://github.com/not-fl3/miniquad/blob/8b8dc6225693ef8c461a0cd44724e33baa9d9fe0/src/graphics/gl.rs#L904
I found that this line adds textures and on my machine this vector only grows and does not decrease. That is why there is a leak. I am trying to figure out the difference with the 0.4.13 version to understand how it freed them.

[KurlykovDanila]

https://github.com/not-fl3/miniquad/blob/8b8dc6225693ef8c461a0cd44724e33baa9d9fe0/src/graphics/gl.rs#L904 I found that this line adds textures and on my machine this vector only grows and does not decrease. That is why there is a leak. I am trying to figure out the difference with the 0.4.13 version to understand how it freed them.

Most likely, this is not the problem, because this vector is never cleared. (In any version, ever)