GPU memory not freed after unmounting Deck component.

[Lowhearth]

Description

GPU memory not freed after unmounting Deck component.

Repro Steps

• Go to https://deck.gl/#/examples/core-layers/

• Open Google Chrome task manager and enable the GPU Memory column.

• Switch between the demos and see how the GPU Memory permanently increases every time a new one is displayed

Environment (please complete the following information):

• Framework Version: 7.0.3
• Browser Version: Chrome 73.0
• OS Ubuntu 18.04.2 LTS

Logs

[Pessimistress]

@tsherif @ibgreen There are several layers to this issue:

• Buffers are not properly deleted, addressed in Finalize all layers #3044. We can not tell WebGLContext to immediately free all GPU resources, according to https://stackoverflow.com/questions/23598471/how-do-i-clean-up-and-unload-a-webgl-canvas-context-from-gpu-after-use. With the above PR I do see GPU memory stack up but it eventually comes back down.
• We do not properly free cached shaders and programs upon finalization, https://github.com/uber/luma.gl/blob/master/modules/core/src/lib/shader-cache.js#L25 I don't have hard numbers on exactly how much impact this has.

[tsherif]

I don't think we should worry too much about the shaders. If buffers and textures are now properly released, that should address this issue.

[ibgreen]

That would be my sense as well.

But maybe they hold on to the context, preventing it from being garbage collected?

[tsherif]

Oh, interesting point. Is unmounting a deck.gl component meant to completely release the gl context?

[ibgreen]

Is unmounting a deck.gl component meant to completely release the gl context?

Hmm, I would have to check the code to answer that. The ideal resource management design is typically that release is "symmetric" with creation, so if we create during mount then yes.

Regardless, when we are done with the context it makes sense to make sure we don't prevent garbage collection by e.g. having objects in e.g. a global map like a shader cache referencing it.

[Pessimistress]

Partial fix published in 7.0.4