Memory leak when restarting render in Solaris viewport

**Describe the bug**
When rendering a heavy groom, the memory usage grows every time I restart the render up to the point where I have to quit Houdinin and restart it after a handful of restarts. The scene is very simple, a bit of geometry, a heavy groom, a hair shader and a skydome.

**To Reproduce**
Steps to reproduce the behavior:
1. Load the repro scene (contact me for access to the customer scene)
2. Render in Solaris
3. Restart the render. Every time you restart the render, the startup memory grows.

**Expected behavior**
A clear and concise description of what you expected to happen.

**Screenshots**


**Used Software Versions**
- Arnold: 7.1.4
- USD:
- Compiler: [e.g. GCC 4.8.5]
- OS: Windows, Linux
- Any 3rd-party app: Houdini 19.5.368

**Additional context**

Obtain the repro scene, then render it in the Solaris viewport and repeat the render restart while monitoring startup memory. Confirm the leak and define done as memory remaining stable across repeated restarts; no source files or tests are identified in the issue.

Written by the indexing model from the issue text.