(Case 1277297) Calling Resources.Load() while asynchronously loading assetbundle makes app freezed

Kichang-Kim · September 12, 2020, 4:09am

Hi. I found app freezing issue related to Resources.Load() and AssetBundles.

If you calling Resources.Load() while asynchronously loading other assets from AssetBundle by using UnityWebRequest, main thread is freezed.

This only occurred on Android/iOS device, not Editor. And reproduced by both Unity 2020.2.0b2 and 2020.1.5f1.

Minimal reproducible project was sent as Case 1277297.

LeonhardP · September 14, 2020, 11:19am

Thanks for the report @Kichang-Kim , we’re looking into it.

Kichang-Kim · September 16, 2020, 10:20am

Kichang-Kim · September 28, 2020, 12:06am

I received the response from Unity that “async/await” makes this freezing issue, but I highly doubt it because async/await does not made any special things itself.

I re-created same reproducible project without async/await and sent modified scripts.

Also found that calling Resourceds.Load in UnityWebRequestAsyncOperation.completed makes 100% freezing.

Kichang-Kim · February 18, 2021, 6:15am

I reported non async/await version of 100% reproducible project as Case 1310359. I hope that this help Unity developers to find and fix freezing issue.

ci_playflock · February 18, 2021, 10:31am

Hi!
We also encountered this problem. Could you please attach a link to Case 1310359 here?

Kichang-Kim · February 18, 2021, 12:32pm

Unity said 1310359 is merged to 1277297 internally. So you can track ticket status in above link.

LeonhardP · February 18, 2021, 2:13pm

We have a fix for this issue in review. Backport requests for 20.2 and 21.1 are also going to be evaluated.

ci_playflock · February 19, 2021, 10:42am

Thank you for your reply
We use the latest lts Unity for production builds. Is there plans to backport the fix to the 2019.4? We have checked versions 2019.4.9-2019.4.20 and we have the problem there. 2019.4.8 works ok, but we need update for Unity IAP and it needs update of the Unity to the latest version.

LeonhardP · February 19, 2021, 3:47pm

Hi @ci_playflock ,

The issue reported by @Kichang-Kim was introduced by changes exclusive to version 20.1 and newer. So what you’re experiencing must be a similar yet different problem. Could you please submit a bug report for it with a reproducible attached?

ci_playflock · February 24, 2021, 1:33pm

Hi, LeonhardP,

Thank you for your response. We will try to reproduce the bug and will send report

CodeBombQuinn · March 4, 2021, 11:25pm

I’m also on 2019.4.21f1 and experiencing something similar. It’s definitely asset bundle related, I thought it might be addressable related so I posted a forum post here:

LeonhardP · March 5, 2021, 12:02pm

Hi everybody,

Quick update and correction of my previous statement. We were now able to reproduce the issue reported by @Kichang-Kim in 2019.4 and the fix is being backported. So this might very well be the same problem you’re seeing in your projects @ci_playflock @CodeBombQuinn .

ci_playflock · March 11, 2021, 1:53pm

Hi @LeonhardP
Thank you for your reply! Are there any approximate predictions when the fix will be accepted in 2019.4?

LeonhardP · March 12, 2021, 11:49am

It was merged to the 19.4 branch two days ago and should be part of the 2019.4.23f1 release.

levelappstudios · March 12, 2021, 6:04pm

Hi, we are expecting for the update too. There is an issue with our game (Unity 2019.4.21), it’s using AssetBundles with async loading resulting in a very long loading times for some devices (Nexus 5X). Maybe could it be related with this case.

I tried to do a quick switch to Unity 2021 for checking the fix, but some libraries are not compatible so we will wait for the 2019 release.

I hope it go out soon.

CodeBombQuinn · March 30, 2021, 7:12pm

Just confirmed Android working for me now on multiple play throughs with 2019.4.23f1! Thanks for the fix!

better_walk_away · June 14, 2022, 4:49pm

Is there a download link to the bug-reproducing project? I’m using 2019.4.22f1 and I’m using Resources.Load and Addressables.LoadAssetAsync at the same time somewhere in my project. But I have never encountered this issue up until now. I guess it needs some other preconditions to trigger this bug.

better_walk_away · June 14, 2022, 6:02pm

I found that if I only allowed one Addressables.LoadAssetAsync command at a time, I could avoid the freeze. So I think if we load multiple AssetBundles asynchronously, we are at risk of app freezing.

Edit: The freeze still occurred after all, but it was related to using Resources.Load while asynchronously loading an asset bundle.

better_walk_away · July 24, 2022, 3:47am

I encountered this issue sparsely in my project. I am using Unity 2019.4.22f1, which is the version that this fix hasn’t been backported. I saw there were indeed “Resources.Load” and “AssetBundleLoadFromAsyncOperation” presented in the same thread. However, I am struggling to reproduce this issue in an empty project. Upgrading Unity engine version is considered a much greater risk in my workplace, workaround is preferred. Can anyone send me a project that can reproduce this issue?

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