How to increase Heroku 30s h12 timeout

I'm running a rails app, which has a json webservice call from a local client developed in c++ (a post command with a multipart json form, uploading a streamed file) I already read on Heroku docs about routing mesh, mentioning the 30s Heroku limit for http connections, and about the long polling alternative, referring to worker dynos. During my call I process pdf documents and insert a signature into them. This pdf documents can either be 100kb or 11Mb (or perhaps more). I understand that I'll eventually have to do this action on a background process, but I would like to avoid doing it before I absolutely have to. Do you know of any way of increasing this timeout? As you may see in my code below, I am processing my document after it gets saved (I was doing this inside an `after_save`, but changed to the controller hoping to send the response before processing). I would so expect that the client would get a response before the document processing, but I'm still having a timeout on the heroku side, and an error on my client side. This all works fine with smaller documents, but for a 121 pages pdf document with only 400kb, it blows off.. In the end, my file gets uploaded, so all I need is for that response to proceed to my client app before the timeout response is sent... Any suggestions? my error: ``` at=error code=H12 desc="Request timeout" method=POST path=/documents host=fierce-beach-2720.herokuapp.com fwd="81.193.155.217/bl4-155-217.dsl.telepac.pt" dyno=web.1 queue=0ms wait=0ms connect=1ms service=32272ms status=503 bytes=0 ``` my controller : ``` respond_to do |format| if @document.save! format.html { redirect_to root_path, :flash => { :success => 'Document was successfully created.'} } format.json { render json: @document, status: :created, location: @document} @document.document_process ```