使用Thin或根本不进行流式传输时流式传输速度较慢

Question

我写了一个小脚本，用Sinatra和Thin:每字节流式传输一个文件

#!/usr/bin/env ruby
require 'sinatra'
require "sinatra/streaming"
get '/' do
  stream do |out|
    File.open("/usr/share/doc/ia32-libs/copyright", "r") do |fd|
      fd.each_byte do |byte|
        break if out.closed?
        putc byte.chr
        out << byte.chr unless out.closed?
      end
    end
  end
end

如预期：

% ruby streamer.rb
== Sinatra/1.3.2 has taken the stage on 4567 for development with backup from Thin
>> Thin web server (v1.4.1 codename Chromeo)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:4567, CTRL+C to stop

% curl http://127.0.0.1:4567

文件内容在两侧写入stdout

如果我删除线路putc byte.chr，那么服务器崩溃并被kill -9 杀死

---

如果我将此脚本更改为模块化样式并添加config.ru:，我会遇到另一个意想不到的行为

#!/usr/bin/env ruby
require 'sinatra/base'
require "sinatra/streaming"
class TestStreamer < Sinatra::Base
  helpers Sinatra::Streaming
  get '/' do
    stream do |out|
      File.open("/usr/share/doc/ia32-libs/copyright", "r") do |fd|
        fd.each_byte do |byte|
          break if out.closed?
#          putc byte.chr
          out << byte.chr unless out.closed?
        end
      end
    end
  end
end

config.ru:

$:.unshift(File.join(File.dirname(__FILE__)))
require 'rubygems'
require 'sinatra/base'
require 'streamer_modular'
map '/' do
  run TestStreamer
end

它启动：

% thin start
>> Using rack adapter
>> Thin web server (v1.4.1 codename Chromeo)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:3000, CTRL+C to stop

但当我请求时，文件的发送速度非常慢，在30秒左右就会关闭。Sinatra在这种情况下没有崩溃。

% time curl -v http://127.0.0.1:3000
* About to connect() to 127.0.0.1 port 3000 (#0)
*   Trying 127.0.0.1... connected
* Connected to 127.0.0.1 (127.0.0.1) port 3000 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.21.0 (x86_64-pc-linux-gnu) libcurl/7.21.0 OpenSSL/0.9.8o zlib/1.2.3.4 libidn/1.15 libssh2/1.2.6
> Host: 127.0.0.1:3000
> Accept: */*
> 
< HTTP/1.1 200 OK
< X-Frame-Options: sameorigin
< X-XSS-Protection: 1; mode=block
< Content-Type: text/html;charset=utf-8
< Connection: close
< Server: thin 1.4.1 codename Chromeo
< 
* Closing connection #0
This package was cre
curl -v http://127.0.0.1:3000  0,01s user 0,00s system 0% cpu 32,559 total

当我删除流助手时，文件会被写入服务器端的stdout，不会有任何延迟：

#!/usr/bin/env ruby
require 'sinatra/base'
require "sinatra/streaming"
class TestStreamer < Sinatra::Base
  helpers Sinatra::Streaming
  get '/' do
#    stream do |out|
    begin
      File.open("/usr/share/doc/ia32-libs/copyright", "r") do |fd|
        fd.each_byte do |byte|
        #  break if out.closed?
          putc byte.chr
        #  out << byte.chr unless out.closed?
        end
      end
    end
  end
end

---

% ruby -v
ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]
% gem list
*** LOCAL GEMS ***
backports (2.6.2)
bundler (1.1.5, 1.1.3)
daemons (1.1.8)
eventmachine (0.12.10)
rack (1.4.1)
rack-protection (1.2.0)
rack-test (0.6.1)
sinatra (1.3.2)
sinatra-contrib (1.3.1)
thin (1.4.1)
tilt (1.3.3)
% gem update
Updating installed gems
Nothing to update
% ls -al /usr/share/doc/ia32-libs/copyright
-rw-r--r-- 1 root root 607403  2. Jan 2012  /usr/share/doc/ia32-libs/copyright
% head -n2 /usr/share/doc/ia32-libs/copyright
This package was created by Daniel Jacobowitz <[e-mail]> on Sun, Aug
8th, 2004.  It was based on the ia32-libs package by Bdale Garbee

我是不是错过了什么？你能复制这个吗，也许能为我找到一个变通办法？

Answer 1

在这种模式下，在Thin上逐字节流式传输有点效率低下，因为由于Thin是基于EventMachine的，所以需要大量的调度和延迟（因此Mike对Thin上的流式传输不起作用发表了评论，Mike可能有Rails背景，而在Thin中这种流式传输确实不起作用）。

但是，Thin（和任何机架式服务器）应该能够直接流式传输文件：

get '/' do
  File.open("/usr/share/doc/ia32-libs/copyright", "r")
end