Hydra render delegate crash in usdview when updated to 24.05 RC1

Community Hydra
1

Hi,

I’m currently working on getting our Hydra render delegate updated against USD 24.05 RC1. I’m running into crashes while testing the render delegate in usdview with the kitchen scene.

Enabling either PXR_WORK_THREAD_LIMIT=1 or USDIMAGINGGL_ENGINE_ENABLE_SCENE_INDEX=1 causes the crash to disappear.

The render delegate is working fine with many previous versions of USD, including USD23.11

I’m wondering what has changed that I’m not accounting for ? Any hints would be appreciated !

Below a representative stack trace. This is from a debug build, but crashes are also happening in release.

image
image1137×864 195 KB

2

A lot of the crashes seem to be hitting code that was added with this commit: [Hd] Add a per-thread single-entry LRU cache for scene · PixarAnimationStudios/OpenUSD@bce5704 · GitHub

In particular the clearing of the per-thread cache triggers the crashiness.

3

Does this crash occur with HdStorm or HdPrman? We haven’t seen any related crashes, and the thread local cache you’re describing has been a great performance optimization for us. But depending on configuration, obviously thread local stuff has a lot of potential to cause chaos…

4

I tracked this down to a problem in our render delegate. There was some problematic dirtying of prims in the sync phase.