Using HTTP/1.1 and permanent connections

Eric Wong normalperson at yhbt.net
Fri Apr 16 16:09:18 EDT 2010


Iñaki Baz Castillo <ibc at aliax.net> wrote:
> Hi, I know that Unicorn forces TCP disconnection as it's explained at
> the top of lib/unicorn/http_response.rb:
> 
>   # A design decision was made to force the client to not pipeline or
>   # keepalive requests.  HTTP/1.1 pipelining really kills the
>   # performance due to how it has to be handled and how unclear the
>   # standard is.  To fix this the HttpResponse always gives a
>   # "Connection: close" header which forces the client to close right
>   # away.  The bonus for this is that it gives a pretty nice speed boost
>   # to most clients since they can close their connection immediately.
> 
> 
> However I want to try TCP permanent connections from the client (or a
> proxy) to Unicorn. I've tryed to modify same file as above by changing
> at the end:

<snip>

> But of course this is not enough and it fails. Not sure what exactly
> happens, it seems that a Unicorn worker doesn't process requests
> anymore until replying the first response.
> 
> So I would like to know if it's feasible to make Unicorn work in
> persistent mode.
> NOTE: I already know that the current design is really good, better
> than using persistent connections, but I want to experiment with
> persistent connections for other purposes I will explain in a future.

Hi Iñaki,

Unicorn won't try to read further requests from the socket (see
process_client() in lib/unicorn.rb).

However, you can use Rainbows! without specifying a concurrency model at
all (or "use :Base").  That way you'll get proper HTTP/1.1 keepalive
support and you can control keepalive_timeout:

# both of these values are the defaults for unconfigured Rainbows!
Rainbows! do
  use :Base
  keepalive_timeout 5
end

-- 
Eric Wong


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