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Fixed in 2020.2.X

Fixed in 2019.4.X, 2020.1.X

Votes

0

Found in

2019.3

2019.3.9f1

2020.1

2020.2

Issue ID

1243010

Regression

No

[WebGL] Async Tasks do not run on WebGL when Threading is enabled

WebGL

-

Reproduction steps:
1. Open the attached project ("case_1243010-WebG-Threads.zip")
2. Open the repro scene ("SampleScene")
3. Enter Play Mode
4. Notice the logs about async tasks being printed out to the screen
5. Exit Play Mode and make a WebGL build
6. Run the build and inspect the printed messages on the screen

Expected result: Async task messages are printed to the screen
Actual result: Only 'Start' and 'End' messages are printed to the screen (async tasks doesn't run)

Reproducible with: 2019.3.14f1, 2020.1.0b9, 2020.2.0a11
Couldn't test with 2018.4 (errors when building the project)

Tested with: Chrome (81.0.4044.138)

  1. Resolution Note (fix version 2020.2):

    IL2CPP wasn't generating the correct threaded code when threadingSupport flag was set in the project settings. Fixed in 2020.2.0a16

  2. Resolution Note (fix version 2020.1):

    Fixed in 2020.1.0b17.4177

  3. Resolution Note (fix version 2019.4):

    Fixed in - 2019.4.7f1

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Comments (8)

  1. Duardo712

    Jun 30, 2023 23:45

    The plugin I commented about below actually caused my project to crash after a while, so I don't recommend using it (I believe it makes everything single-threaded, even the Editor code). A simpler solution I came up with was:

    1. Define a singleton GameObject.
    2. Define a replacement for Task.Delay which returns a Task generated from a TaskCompletionSource. The task completes after the desired delay, using the singleton's StartCoroutine to implement the waiting.

  2. Duardo712

    Jun 30, 2023 20:48

    2021.3.19f1 still not working. A workaround is to download Mono.Cecil from NuGet and use https://github.com/VolodymyrBS/WebGLThreadingPatcher. I did this and it worked.

  3. Siccity

    Jul 29, 2022 09:00

    Still not fixed in 2019.4.26f1

    Just found this out after replacing all my coroutines with async/await :D

  4. AndersenCastaneda

    Jul 07, 2022 19:07

    Task.Delay() is implemented for WebGL, but it uses a System.Timer, which requires threading support, and because of that is not compatible.
    code source: https://github.com/Unity-Technologies/mono/blob/unity-mono-4.8.0-branch/mcs/class/referencesource/mscorlib/system/threading/Tasks/Task.cs#L5909

    Replace Task.Delay() with Task.Yield() and the code will work on WebGL.

  5. jacobsmith3204

    Jan 23, 2022 03:43

    I've tried this in 2020.3.26f1, 2019.4.34.f1 (LTS) and 2019.4.7f1
    and none of those have worked. (first 2 being the latest (LTS) builds)

  6. David_GameDev

    Jan 20, 2022 14:16

    Can confirm, still not working in 2021.2.7f1

  7. Tom-Mensink

    Feb 22, 2021 19:33

    Why is this closed, doesn't work in 2019.4.8f1 either.

  8. vvmichalk

    Jan 13, 2021 12:31

    Just tested in 2019.4.7f1, it does not work.
    Simple thing like this does not work:

    Test.text = "1";
    await Task.Delay(1000);
    Test.text += "2";
    await Task.Delay(1000);
    Test.text += "3";

    Unity only pretends it's multi-platform, it's actually multi-pain.

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