Rails dynamic streaming doesn't work. At least sometimes. While the Rails documentation, and all the euphoric comments in the community feature code examples along the lines of

  
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# Renders "Hello from code!"
render :text => proc { |response, output| 
  output.write("Hello from code!") }

But this just doesn't work as not-really-advertised. The reason? While rails correctly - that is to say in the way it is documented - does write directly to the output stream, at least with Mongrel the output stream is just a String.

So whatever you are doing: the entire request is still collected in RAM. Bummer!