控制套接字
@control_socket
绑定到9799端口,并生成4个工作进程等待接受连接。每个工作进程所完成的工作如下:def spawn_child
fork do
$STDOUT.puts "Forking child #{Process.pid}"
loop do
@client = @control_socket.accept
loop do
request = gets
if request
respond(@inner_app.call(request))
else
$STDOUT.puts("No Request")
@client.close
end
end
end
end
end
我使用了一个非常简单的Rack应用程序,它只返回一个带有状态码200和Content-Type为text/html的字符串。
我的问题是,当我使用像
read
或read_partial
或read_nonblock
这样的读取方式时,我的服务器无法正常工作,但如果我使用gets
来读取传入请求(通过“http://localhost:9799”访问URL),则可以正常工作。当我使用非阻塞读取时,它似乎从未抛出EOFError,根据我的理解,这意味着它没有接收到EOF状态。这会导致读取循环无法完成。以下是执行此操作的代码片段。
# Reads a file using IO.read_nonblock
# Returns end of file when using get but doesn't seem to return
# while using read_nonblock or readpartial
# The fact that the method is named gets is just bad naming, please ignore
def gets
buffer = ""
i =0
loop do
puts "loop #{i}"
i += 1
begin
buffer << @client.read_nonblock(READ_CHUNK)
puts "buffer is #{buffer}"
rescue Errno::EAGAIN => e
puts "#{e.message}"
puts "#{e.backtrace}"
IO.select([@client])
retry
rescue EOFError
$STDOUT.puts "-" * 50
puts "request data is #{buffer}"
$STDOUT.puts "-" * 50
break
end
end
puts "returning buffer"
buffer
end
然而,如果我使用简单的
gets
代替read
或read_nonblock
,或者用break
替换IO.select([@client])
,代码将完美运行。
这里是代码可以运行并返回响应的情况。我想使用read_nonblock的原因是unicorn使用了一个相当的等效物,在kgio库中实现了非阻塞读取。
def gets
@client.gets
end
整段代码如下。
module Server
class Prefork
# line break
CRLF = "\r\n"
# number of workers process to fork
CONCURRENCY = 4
# size of each non_blocking read
READ_CHUNK = 1024
$STDOUT = STDOUT
$STDOUT.sync
# creates a control socket which listens to port 9799
def initialize(port = 21)
@control_socket = TCPServer.new(9799)
puts "Starting server..."
trap(:INT) {
exit
}
end
# Reads a file using IO.read_nonblock
# Returns end of file when using get but doesn't seem to return
# while using read_nonblock or readpartial
def gets
buffer = ""
i =0
loop do
puts "loop #{i}"
i += 1
begin
buffer << @client.read_nonblock(READ_CHUNK)
puts "buffer is #{buffer}"
rescue Errno::EAGAIN => e
puts "#{e.message}"
puts "#{e.backtrace}"
IO.select([@client])
retry
rescue EOFError
$STDOUT.puts "-" * 50
puts "request data is #{buffer}"
$STDOUT.puts "-" * 50
break
end
end
puts "returning buffer"
buffer
end
# responds with the data and closes the connection
def respond(data)
puts "request 2 Data is #{data.inspect}"
status, headers, body = data
puts "message is #{body}"
buffer = "HTTP/1.1 #{status}\r\n" \
"Date: #{Time.now.utc}\r\n" \
"Status: #{status}\r\n" \
"Connection: close\r\n"
headers.each {|key, value| buffer << "#{key}: #{value}\r\n"}
@client.write(buffer << CRLF)
body.each {|chunk| @client.write(chunk)}
ensure
$STDOUT.puts "*" * 50
$STDOUT.puts "Closing..."
@client.respond_to?(:close) and @client.close
end
# The main method which triggers the creation of workers processes
# The workers processes all wait to accept the socket on the same
# control socket allowing the kernel to do the load balancing.
#
# Working with a dummy rack app which returns a simple text message
# hence the config.ru file read.
def run
# copied from unicorn-4.2.1
# refer unicorn.rb and lib/unicorn/http_server.rb
raw_data = File.read("config.ru")
app = "::Rack::Builder.new {\n#{raw_data}\n}.to_app"
@inner_app = eval(app, TOPLEVEL_BINDING)
child_pids = []
CONCURRENCY.times do
child_pids << spawn_child
end
trap(:INT) {
child_pids.each do |cpid|
begin
Process.kill(:INT, cpid)
rescue Errno::ESRCH
end
end
exit
}
loop do
pid = Process.wait
puts "Process quit unexpectedly #{pid}"
child_pids.delete(pid)
child_pids << spawn_child
end
end
# This is where the real work is done.
def spawn_child
fork do
$STDOUT.puts "Forking child #{Process.pid}"
loop do
@client = @control_socket.accept
loop do
request = gets
if request
respond(@inner_app.call(request))
else
$STDOUT.puts("No Request")
@client.close
end
end
end
end
end
end
end
p = Server::Prefork.new(9799)
p.run
请问为什么使用read_partial
、read_nonblock
或read
时读取失败。希望能得到帮助。
EOFError
,read_nonblock
等的说明相反。get
应该返回nil
,read_nonblock
应该引发EOFError
。 - Michael Sladespawn_child
方法中分配实例变量@client
很奇怪。每个工作进程不会覆盖该变量吗?或者,fork会建立自己的上下文? - GSP