ExecutionContext does not flow consistently

[dotnet]

ExecutionContext does not flow consistently

[LeeCampbell]

In my opinion this is something in Rx that is better than in TPL. I find it quite offensive that TPL forces me to opt out of the implicit thread switching. Rx is free threaded by design, and I imagine many consumers would be shocked to see it change (as it is a breaking change). As a reminder some of us have been using Rx for +4 years and that would be quite a change to our code bases to have to unpick all the ExecutionContext switching this would introduce to get back our performance. I suggest looking at a solution using ObserverOn and a Scheduler that maintained Execution context.

[bartdesmet]

We've discussed this at length back in the day when we were designing Rx. Lee's explanation on the free threaded nature is spot on. In Rx, one has to explicitly parameterize concurrency using mechanisms such as ObserveOn.