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Not sure if this makes it any better, but a bit later on they talk more about how the STW scheme will work. They call each thread which is not the concurrent GC a mutator, and part of the GC scheme will be ensuring that a mutator thread be stopped for less than 1ms, and that the 1ms pause should not stop any other mutator threads. If they can manage it, this scheme sounds promising for most soft real time programs.

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I read them to mean that the one GC thread would stop the world for no more than 10 out every 50 ms, and in addition the concurrent garbage collector could ask any mutator thread to pause and do no more than 1 ms worth of GC work during any 40 ms non-STW period.

So in terms of real time, your deadlines could be no less than 11 ms.

That's not how I understood it. It says they're doing a hybrid STW and concurrent GC.

(a) A mutator may be stopped for up to 10 ms of every 50 ms by the STW collector.

(b) If more collection is needed, it will transition to a concurrent collector for the remaining 40 ms. Concurrent may pause stop a mutator for up to an additional 1 ms.

Therefore the worst case is 10 + 1 = 11 ms, not 1 ms.

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