Re: nginx reverse proxy getting ECONNRESET

[Eric Wong <e@80x24.org>]

Michael Fischer <mfischer@zendesk.com> wrote:
> On Tue, Mar 24, 2015 at 10:59 PM, Eric Wong <e@80x24.org> wrote:
> > Another likely explanation might be you're not draining rack.input every
> > request, since unicorn does lazy reads off the socket to prevent
> > rejected uploads from wasting disk I/O[1]
> >
> > So you can send a bigger POST request with my example to maybe
> > reproduce the issue.
> >
> > [1] you can use the Unicorn::PrereadInput middleware to forcibly
> >     disable the lazy read:
> >     http://unicorn.bogomips.org/Unicorn/PrereadInput.html
> 
> Actually, these are quite large POST requests we're attempting to
> service (on the order of 4MB).  Can you elaborate on the mechanism in
> play here?

Unlike a lot of servers, unicorn will not attempt to buffer request
bodies on its own.  You'll need to actually process the POST request in
your app (via Rack/Rails/whatever accessing env["rack.input"]).

The PrereadInput middleware makes it behave like other servers
(at the cost of being slower if a request is worthless and rejected)

So there might be data sitting on the socket if your application
processing returns a response before it parsed the POST request.

In this case, the ECONNRESET messages are harmless and saves your
Ruby process from GC thrashing.

Actually, you can try setting up a Rack::Lobster instance but sending
a giant POST request?

------------- config.ru --------------
require 'rack/lobster'
run Rack::Lobster.new
--------------------------------------