Unity Issue Tracker - Semaphore.WaitForSignal under Canvas.BuildBatch causes a slow editor in Play mode

Fixed in 2020.1.X

Fixed in 2018.4.X, 2019.3.X

Votes

41

Found in

2018.4

2019.2.0a1

2019.2.1f1

2019.3.0a1

2020.1.0a1

Issue ID

1178300

Regression

Yes

Semaphore.WaitForSignal under Canvas.BuildBatch causes a slow editor in Play mode

Visual Effects - Legacy

Aug 21, 2019

Steps to reproduce:
1. Open the attached project "Temp Project" from the ownCloud link
2. Open "Main Scene"
3. Turn on the Profiler window
4. Enter Play mode
5. Notice the Spikes from Semaphore.WaitForSignal

Expected results: Semaphore.WaitForSignal does not cause spikes in the Profiler window and making Editor slow
Actual results: Semaphore.WaitForSignal causes spikes in the Profiler window and makes Editor slow

Reproducible with: 2019.2.3f1, 2019.3.0b1, 2020.1.0a1

Note: 2019.1 breaks the project and its packages

richardkettlewell

Oct 16, 2019

We are working on a fix for this.

Comments (39)

F_o

Jan 02, 2021 13:05

I am still experiencing this issue in 20.1.3f1
Arcadian-Unity

Oct 19, 2020 12:58

Not fixed, 2019.4.10f1
KingLlama

Aug 19, 2020 07:00

This is still broken for unity 2019.4.0f1.
Al3xBRB

Aug 10, 2020 08:27

Not fixed in 2019.4.0f1.
TsdTeam

Jul 23, 2020 09:10

Not fixed in 2019.4.4f1
BrettCroomo

May 26, 2020 10:36

Still having this issue in 2019.3.13f using near empty scene in HDRP 7.3..
Base line is 14.5ms then will eventuially spike to 76.6ms. Spike repeats every few seconds.
Seems to align with "CreateCommittedResourceWithTag" under "BufferD3D12.InitializeResource" on the render thread.
UDN_6c8b8a3a-8d7a-436e-9ca9-a1bf7a57bf0c

May 10, 2020 05:00

2020.1.0a25 also has the issue.
In my simple project, iphone6 and android has no issue，but my iphone11 pro max has the issue.
UDN_6c8b8a3a-8d7a-436e-9ca9-a1bf7a57bf0c

May 10, 2020 04:30

2019.3.7f1 already has the issue.
PyramidGames

Apr 28, 2020 10:37

2019.3.7f1 still no fixed
RedVonix

Apr 08, 2020 01:09

Reproduced in 2019.3.7f1