App eats memory when HMDUnmounted (Windows)

Participant

@vrdaveb We aren't using the OVROverlay, or any of the Oculus Utilities at this moment. (Since upgrading to Unity 5.4, we actually pulled out all of the OVR bits and were just using the "Oculus" in the VR selection in the Unity build settings.) Unless perhaps the OVROverlay is being used behind the scenes somewhere? The canvas we're using is a "Screen Space - Camera" canvas, but I don't think that would be using OVROverlay behind the scenes?

I was trying to see if I could re-create the issue in a fresh project, and I'm not even able to duplicate the same behavior: Removing the HMD doesn't "blackout" the screen in the fresh project like it does in my main application. It does however stop the rendering on the last frame it drew. (The OpenVR SDK allows rendering to continue while the HMD is removed, so I was at least sure that I'm using the Oculus SDK through the unity option.)

Is there something with that blackout being drawn that could be using the OVROverlay? I certainly can't seem to figure out why that's being generated in my main app, but not in the tiny fresh project I made. The fresh project certainly isn't leaking anything! Hmm.

I've asked my boss if I'm able to send you a build, but in the mean time I figured I'd see if I could provide some more information here.

Empty-OculusLeak-Project.zip

Participant

Alright, I've managed to narrow it down further: I'm seeing the issue when I have a "Screen Space - Camera" canvas, that has a child with an Image.

Further, the "Run In Background" seems to be the issue yet again: Checked, removing the HMD will black the screen and the memory will leak. Unchecked, removing the HMD causes rendering to stop, but memory does not leak.

Unfortunately, running in the background is a critical feature of our application. (The Unity window on the PC will often be minimized while the Rift is in use.)

Using Unity 5.5.0b7, I've attached a project named "Empty-OculusLeak" to this post that replicates the issue. In the scene 'Main', you'll find a Camera, as well as a canvas with the UI.Image as I described above. Building and running while the HMD is unmounted, after the splash image (which I've just set to a random default image for now, because I was replicating our project as closely as possible,) memory usage should start to climb rapidly. Putting on the HMD should cause the memory usage to immediately drop.

Build again, but this time with the "Run in Background" disabled, and observe that the leak does not occur.

For now I'm writing some scripts to disable my Canvas when I'm not drawing something on it to hopefully skirt around this for the time being, but any help would be appreciated!

Inspiring

Unity 5.5 probably doesn't have the leak fix yet. Can you try 5.4.1p4 or higher?

Empty-OculusLeak-5_4_1p4.zip

Participant

I'm seeing the same behavior on 5.4.1p4. I've attached a new project, created with 5.4.1p4. It also has an executable build this time: Empty-OculusLeak-5.4.1p4\build\build.exe.

Perhaps it's also of note that I'm using an x64 build from the x64 editor? I'm not sure how the code paths differ per architecture, but I suppose that could be relevant?

Again, if you just run that build with the Rift unmounted memory usage should start climbing rapidly.

Inspiring

Thanks, looks like the canvas leak was never properly fixed. We're working with Unity to get a proper fix. Unfortunately, you may have to use 5.3.6p7 until we get to the bottom of it.

Participant

I've downloaded the latest tools, and written up a tiny script that checks the state of OVRManager.instance.isUserPresent, toggling my Canvas game object off when they remove the HMD, then re-enabling it when they put it back on. In my limited testing it seems to be an effective workaround for our project, but I'll keep my eyes on patch notes to see when a proper fix makes it's way down the pipeline!

Thanks for your help and quick responses, Dave!

D

digital

Up and Coming

Any update on this?

Inspiring

Unity traced this back to an additional bug in Canvas management. Fixes are planned for 5.3.7p1, 5.4.2p4, and 5.5.0b11. In the meantime, you need to disable Run In Background or disable any Canvases while the app doesn't have VR focus.

D

dbedford

New Participant

5.4.2p4 was released yesterday but it isn't 100% clear to me, from the release notes, that this issue has been fixed. Can you confirm whether this issue was in fact fixed in the 5.4.2p4 release?