On Sun, Sep 2, 2012 at 5:59 PM, Tim Starling <tstarling(a)wikimedia.org> wrote:
The other reason for the existence of the backend
thumbnail store is
to transport images from the thumbnail scalers to the 404 handler. For
that purpose, the image only needs to exist in the backend for a few
seconds. It could be replaced by a better 404 handler, that sends
thumbnails directly by HTTP. Maybe the Swift one does that already.
My understanding is that thumb.php already streamed the thumbnail back
to the 404 handler via HTTP and has done so for at least the past two
years or so.