Memory overflow in Unreal Editor when running blocks environment - Lidar shouldn't render all points by default

[nightduck]

This bug is caused by running code entirely in Airsim's repo. I started the sample blocks environment and executed all the steps to run the tutorial ros packages

The end result is that UnrealEditor begins gobbling up ram, until I kill it or it crashes (sometimes taking my machine down with it, if it resorts to swap space).

Poking around suggests this is a graphics issue. I'm using a GTX 1080 running Nvidia's proprietary 435 drivers on a fresh-ish install of Ubuntu 18.04. ("fresh-ish" = /home directory is recycled from an old build)

[rajat2004]

Hmm, sounds strange, does this happen without running the ROS package, ie. just the Editor? Also, which version of UE are you using, 4.24?
You could also try using OpenGL instead of the Vulkan drivers which UE now uses by default. Vulkan does take up more memory right now, but hopefully, some of the memory issues might be fixed in UE 4.25
For using OpenGL, just use the -opengl4 option while launching Editor from the terminal

[nightduck]

If I run the blocks simulation totally as is, it'll run fine. When I copy over the front_stereo_and_center_mono.json into Documents/Airsim/settings.json and the lidar dots show up, that's when the problem appears. At first, it appeared to be a low frame-rate issue, but the fix discussed in issue #1185 did nothing.

Yes, UE 4.24

I wasn't aware openGL was an option. I tried that flag you suggested. UE says upon opening:

Trying to force OpenGL RHI but the project does not have it in TargetedRHIs list

Applied this fix and it warned "OpenGL deprecated. Please use Vulkan" upon bootup.

Once I get to the simulation. The memory bug appears to be gone. So..fixed? Still getting 1-2fps

[rajat2004]

Yes, sorry forgot to mention, follow the first comment in https://www.reddit.com/r/unrealengine/comments/e4i7ny/cannot_start_unreal_engine_4_in_linux/

The FPS could be due to all the cameras enabled, try removing those and see if it improves. There's an open PR to improve the speed of image capture

[nightduck]

Unclear on how to disable cameras. Also, which ones. I tried deleting one, and UE crashed.

[rajat2004]

Just remove from the settings if not required

[nightduck]

The fix was to go into settings.json and set DrawDebugPoints to false. The debug points cumulatively add up and bog down Unreal Engine.

Consider this issue now a feature request: Lidar, by default, shouldn't render all points ever captured, only recent ones, say from the last frame.

[rajat2004]

This problem didn't occur with me when I was using Lidar. But it could be the case that I just didn't leave it on that much
Now that I think about it, I haven't actually used it on UE 4.24, so it might be different. How much time did it take to hog up the memory and crash the system?

Also, by default, DrawDebugPoints is False

[nightduck]

It would take about 5-10 seconds for the framerate to drop to rock bottom. The render time for each frame increases linearly, so the fps has a 1/x relationship. Once it gets down to 2-3fps, it gobbles up a gig of ram every 3-4 seconds or so. If your system doesn't have swap space, only UE will crash, not the OS. Either way, it's directly related to memory usage.

And both the settings files that specify DrawDebugPoints set it to true.

Which version of UE are you using? I can build that and test it on my system. I know that UE switched to Vulkan in 4.21. Anything earlier would use OpenGL, which doesn't have the memory bug, only low frame rates.

[rajat2004]

#2614 has been merged, so I think this issue can be closed

[nightduck]

Agreed