Re: [RFC/PATCH] event_machine: lazily set async env keys

[James Tucker <jftucker-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Sorry for the top post, trying to be quick...

Just regarding the async close, it's used primarily when the client disconnects so that you can stop asynchronous operations. It's quite important from a resource standpoint.

Why don't you just use a lambda instead of a method?

lambda { |*args| em_write_response(*args) }

That'd avoid the leak, and provide nearly the same performance profile. In fact on 1.9, lambdas are pretty damn quick.

On 15 Jul 2010, at 07:03, Eric Wong wrote:

> This has the small likelyhood of breaking apps that
> check via:
>  env.include?("async.callback")
> 
> Or any of member?/has_key?/key?, as they're all the same method.
> 
>> From all the async examples I see, I just see apps just
> use env["async.callback"].
> 
> Worth it?
> 
>> From 40ef059dfc99c7daad1b1829713727b86c8fc9a0 Mon Sep 17 00:00:00 2001
> From: Eric Wong <normalperson-rMlxZR9MS24@public.gmane.org>
> Date: Thu, 15 Jul 2010 05:48:29 +0000
> Subject: [PATCH] event_machine: lazily set async env keys
> 
> This is a micro-optimization when running a 'hello world' benchmark and
> also reduces the strength of a memory leak under 1.9.2-rc2:
> 
> http://redmine.ruby-lang.org/issues/show/3466
> ---
> lib/rainbows/ev_core.rb       |    1 -
> lib/rainbows/event_machine.rb |   17 ++++++++++++-----
> lib/rainbows/rev/client.rb    |    1 +
> 3 files changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/rainbows/ev_core.rb b/lib/rainbows/ev_core.rb
> index 5ca693b..357042b 100644
> --- a/lib/rainbows/ev_core.rb
> +++ b/lib/rainbows/ev_core.rb
> @@ -16,7 +16,6 @@ module Rainbows
> 
>    def post_init
>      @remote_addr = Rainbows.addr(@_io)
> -      @env = {}
>      @hp = HttpParser.new
>      @state = :headers # [ :body [ :trailers ] ] :app_call :close
>      @buf = ""
> diff --git a/lib/rainbows/event_machine.rb b/lib/rainbows/event_machine.rb
> index 173340e..14da118 100644
> --- a/lib/rainbows/event_machine.rb
> +++ b/lib/rainbows/event_machine.rb
> @@ -54,6 +54,17 @@ module Rainbows
>      G = Rainbows::G
> 
>      def initialize(io)
> +        @env = Hash.new do |hash,key|
> +          case key
> +          when ASYNC_CALLBACK
> +            hash[ASYNC_CALLBACK] = method(:em_write_response)
> +          when ASYNC_CLOSE
> +            # we're not sure if anybody uses this, but Thin sets it, too
> +            hash[ASYNC_CLOSE] = EM::DefaultDeferrable.new
> +          else
> +            nil
> +          end
> +        end
>        @_io = io
>        @body = nil
>      end
> @@ -71,10 +82,6 @@ module Rainbows
>        begin
>          @env[RACK_INPUT] = @input
>          @env[REMOTE_ADDR] = @remote_addr
> -          @env[ASYNC_CALLBACK] = method(:em_write_response)
> -
> -          # we're not sure if anybody uses this, but Thin sets it, too
> -          @env[ASYNC_CLOSE] = EM::DefaultDeferrable.new
> 
>          response = catch(:async) { APP.call(@env.update(RACK_DEFAULTS)) }
> 
> @@ -143,7 +150,7 @@ module Rainbows
>      end
> 
>      def unbind
> -        async_close = @env[ASYNC_CLOSE] and async_close.succeed
> +        @env.include?(ASYNC_CLOSE) and @env[ASYNC_CLOSE].succeed
>        @body.respond_to?(:fail) and @body.fail
>        @_io.close
>      end
> diff --git a/lib/rainbows/rev/client.rb b/lib/rainbows/rev/client.rb
> index d08992b..0df7415 100644
> --- a/lib/rainbows/rev/client.rb
> +++ b/lib/rainbows/rev/client.rb
> @@ -15,6 +15,7 @@ module Rainbows
>        CONN[self] = false
>        super(io)
>        post_init
> +        @env = {}
>        @deferred_bodies = [] # for (fast) regular files only
>      end
> 
> -- 
> Eric Wong
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