Allow for isolates to share memory of immutable objects

[feinstein]

As far as I understand from the docs, a SendPort will copy the data being transmitted to the ReceivePort, while Isolate.exit() won't copy the data, just pass the object reference to the original Isolate, if both are on the same Isolate Group.

I believe there might be a chance to improve the performance further. If we annotate a class with @immutable, in theory that object could be shared with multiple threads, so we could send it to another Isolate without copying it.

I imagine there might be other complications behind the scenes, but I wanted to suggest if there's a way for us to improve the performance for Isolates.

I thinking about a use case for my trading app, where I need a separate Isolate to receive low latency, real time stock data, parse it into immutable objects, and send them to the main Isolate.

[a-siva]

Please refer to dart-lang/language#125 for a discussion on this feature.

[feinstein]

Thanks @a-siva, I will close this one then.