Single Threaded Async Responses

Single Threaded Async Responses

[James Tucker]

Hi Eric and anyone else listening in,

I completed an async API for Thin quite some time ago well suited to  
some of the design goals you have here. If you're interested we could  
have a chat about supporting the same API designs that allow single  
threaded reactor based concurrent responses. I believe such an API  
would fit well in rainbows too.

Kind regards,

James Tucker

Re: Single Threaded Async Responses

[Eric Wong]

James Tucker <jftucker-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi Eric and anyone else listening in,
>
> I completed an async API for Thin quite some time ago well suited to  
> some of the design goals you have here. If you're interested we could  
> have a chat about supporting the same API designs that allow single  
> threaded reactor based concurrent responses. I believe such an API would 
> fit well in rainbows too.

Hi James,

This sounds interesting.

Does this mean it does synchronous request reading?  That'll mean
it requires nginx in front to work well.

So the response is written asynchronously, meaning it can be bigger than
the outgoing TCP buffers and still not block, right?  I considered
something like this for Unicorn, too, but then I realised that all the
responses I see managed to fit into the TCP buffers without blocking
already.

But for weird OSes with tiny buffers or apps dealing with large
responses it would probably make sense for Rainbows! (especially
if you plan to help me support it into the future :)

Is it merged into Thin already?  Where can/should I take a look?

One bit to be careful for is the body of the Rack response may not be a
simple Array of String objects, so that requires extra effort/cycles to
stringify into something that can be buffered for async writes.  But
then that could be a huge chunk to keep around in memory (since we
mainly need this to support larger responses).  What nginx does is
it will buffer into a temporary file and then sendfile() it over
as the socket becomes readable.

-- 
Eric Wong

Re: Single Threaded Async Responses

[Eric Wong]

James Tucker <jftucker-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi Eric and anyone else listening in,
>
> I completed an async API for Thin quite some time ago well suited to  
> some of the design goals you have here. If you're interested we could  
> have a chat about supporting the same API designs that allow single  
> threaded reactor based concurrent responses. I believe such an API would 
> fit well in rainbows too.

Hi James,

I've looked at Thin and added this as a TODO item for Rainbows! once
EventMachine support gets added.

For now, we also have an a (more Rack-compatible[1] but certain
Unices-only[2]) API which relies on passing file descriptors to Rev in
Rainbows! 0.3.0.

[1] - The only thing that keeps it from running correctly under
      Rack::Lint is that Rack::Lint doesn't pass body#to_path calls
      to up the stack even though it _allows_ it.

[2] - Most Unices seem to support /dev/fd/#{io.fileno}
      to lookup the contents of the file descriptor table.

-- 
Eric Wong