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A comment on Sub-10 ms Latency in Java: Concurrent GC with Green Threads. Parent comment

Re:Sub-10 ms Latency in Java: Concurrent GC with Green Threads by jerrinot on Wednesday August 05, 2020 @09:51AM (#24060711)
I didn't know about fully concurrent root scanning, thank you!

How does root scanning work wrt to Loom? Are stacks of virtual threads treated as roots? I guess there is no other option?

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Re:Sub-10 ms Latency in Java: Concurrent GC with Green Threads by pron on Wednesday August 05, 2020 @09:54AM (#24060742)
No, virtual thread stacks are not roots! This is one of the main design highlights of the current Loom implementation. In fact, at least currently, the VM doesn't maintain any list of virtual threads at all. They are just Java objects, but the GC does treat them specially.
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Re:Sub-10 ms Latency in Java: Concurrent GC with Green Threads by kjeetgill on Wednesday August 05, 2020 @01:51PM (#24063528)
Interesting! In what way are they handled specially?
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Re:Sub-10 ms Latency in Java: Concurrent GC with Green Threads by pron on Wednesday August 05, 2020 @04:27PM (#24065192)
Unlike any other object, the location of references on a stack can change dynamically, so the GC needs to recognise those objects and walk their references differently. There are other subtleties, too.
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