I haven't read the code, but there are 2 areas where I expect allocations: - The continuation which is passed to .then, and which is typically a closure, must

I haven't read the code, but there are 2 areas where I expect allocations: - The continuation which is passed to .then, and which is typically a closure, must be type-erased, which requires an allocation. Storing the continuation in a std::function would allocate too. A short glance at https://github.com/scylladb/seastar/blob/master/core/future.hh https://github.com/scylladb/seastar/blob/master/core/future.... also confirms that there is a make_unique there. - Since continuations are most likely not called inline on completion but deferred into the next eventloop iteration there needs to be a dynamically sized queue to hold the ready continuations. I am not 100% sure if that's the case for seastar too, but I would guess so.