Current state of async load support in editor?

Development Platform & Builds
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I was wondering if Epic can provide any updated information about the current state of async loading support in editor? The last set of info I was able to find was from about a year ago [Content removed] There are a couple of recent posts about bugs in editor when using async loading as well (which also implies there are multiple other licensees using it)- but no concrete list about any known issues/etc when using async loading in editor. Is it expected that it’s likely relatively stable at this point (and Epic just wants to do more testing before enabling it by default) or are there known problems in 5.7/5.8 that would make Epic discourage it’s use?

Any info that can be provided would be appreciated! Thanks!

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Steps to Reproduce
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Hi,

The Async Loading Thread (ALT) in editor is still off by default in the engine, but it has moved a long way since that 5.5-era thread. The Lyra and ShooterGame samples that ship with 5.8 now opt into it in their own project config, as does Fortnite main stream, so I’d say we’re in the hardening phase.

If you want to give it a try:

  • You should use 5.8, not 5.7**.** A set of ALT-in-editor races was caught by our thread-sanitizer coverage and fixed for 5.8, including a blocker-class race in the linker’s import creation. Those fixes did not go back to 5.7.
  • Known problem areas remaining in 5.8: Blueprint compilation being driven from the loading thread, object loading during CDO construction, redirectors touched mid-serialization, and individual asset types that register delegates or do non-thread-safe work in `PostLoad`/`PostInitProperties` (Sequencer, audio and Control Rig assets have all needed fixes). Expect project-specific crashes rather than a clean run.

You can enable the feature in \Config\DefaultEngine.ini

5.8:

[/Script/Engine.EditorStreamingSettings]
s.AsyncLoadingThreadEnabled=True
s.AllowMultithreadedLoading=True

5.7: s.AllowMultithreadedLoading is a plain console variable, you can pass it as `-dpcvars=s.AllowMultithreadedLoading=1` or set it from the [ConsoleVariable] section.

[/Script/Engine.EditorStreamingSettings]
s.AsyncLoadingThreadEnabled=True
 
[ConsoleVariables]
s.AllowMultithreadedLoading=1

Regards,

Patrick