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iOS DisplayLinkManager should be main actor #190725
Description
Use case
Currently DisplayLinkManager is @unchecked Sendable:
And it relies on NSLock for synchronization:
Proposal
Since in iOS embedder ui / platform threads are merged, and there's no way to opt out, we should make it a MainActor (and remove the locks), as this is purely a UI bound concept.
Activity
cbracken commentedon Aug 10, 2026
This will be a while out but agreed that yes, whatever is left of this (if anything) should be
mainActor. Right now there's still a lot of very delicate C++ threading around this.cbracken commentedon Aug 13, 2026
Worth noting that this will cause crashes for certain people creating off-main-thread engines without additional work:
#190909
Whether that's a supported use-case or not is something we'll need to discuss. Assigning to @cbracken @LongCatIsLooong @hellohuanlin purely to come to agreement on how to address that issue and what it means for this one.
cbracken commentedon Aug 13, 2026
We should annotate
[FlutterEngine run]this way too since that's what creates the DisplayLinkManager under the hood.hellohuanlin commentedon Aug 18, 2026
If we encounter a code where we know it must be main actor, but not yet known to the compiler due to C++, we could use
MainActor.assumeIsolatedAPI for that.iOS: Ensure engine is run on the main thread (flutter#191626)