There was an proposal for this in the past: https://github.com/dlecan/play2-war-plugin/pull/169
@dlecan can you comment on this?

My personal idea would be to cut manually the input stream into chunks, pushing them one by one to the body parser (it means we must block until the body parse reach its next state before pushing the next chunk). There would involve blocking, but would still be better than the current situation IMHO.
The blocking could be mitigated by using a dedicated thread pool (or the one from the servlet?)