Search Issue Tracker
Fixed in Unity 2017.3.0f3
All canvases in the Scene is being Rebuilt
There are large CPU spikes related to UI. While trying to track down the symptoms, User has found out that Canvas.BuildBatch encompasses *every* active canvas in the scene and subsequently slows SendWillRenderCanvases.
The problem is that all canvases are being rebuilt rather than only ones in the relevant hierarchy.
The event which causes this appears to be the addition of a GameObject to a ScrollRect's viewport. It's expected in that case that only canvas ancestors of that node are rebuilt, not all canvas in the scene. The codebase does *not* call Canvas.ForceUpdateCanvases().
Steps to reproduce:
1. Open User's attached project ("Test-ScrollandAnotherCanvas.zip")
2. Open Profiler
3. Enter Play mode
4. Wait for objects to stop appearing in scroll list
5. Pause Play mode
6. Look for Canvas.BuildBatch in profiler
7. Check Show Related Object
Result: Check that Overlay is being re-build
Reproduced with: 2017.2.0b3, 2017.1.0f3, 5.6.2p3.
Note: Sometimes it is easy to reproduce when the list is already filled, but sometimes not. So to reproduce it easily, move the scroll list when the items are being created.
All about bugs
View bugs we have successfully reproduced, and vote for the bugs you want to see fixed most urgently.
- [HUB] Unable to use HUB 1.6.1 on Windows when the internet is not connected
- Timeline animation asset won't update
- [LWRP] VFX Graph projects have visual artifacts when viewed with certain mobile GPUs
- Particle System with custom simulation space jitters when moved/rotated in Late Update
- Preview Window in the Inspector shows the same Preview image when multiple Terrain layers are selected