Queue/IO blocking in threads


#1

I am coding a client/server in which requests and responses are handled
on the client and server side by threads communicating with Queues
(because several sessions will share one connection to the server).

In the code below, I expect the client and server to exchange the same
message indefinitely, but between reading the queues and IO, it blocks
somewhere. it doesn’t get further than printing the first request.

require ‘gserver’
require ‘socket’
require ‘zlib’
require ‘yaml’

class ConnectionHandler
def initialize(io)
queue = Queue.new
request_handler = Thread.new do
loop do
req = io.gets(“EOF”).chomp(“EOF”)
puts “client request: #{req}”
queue << “speak your request, my child”
end
end

response_handler = Thread.new do
  loop do
    res = queue.pop
    socket << res << "__EOF__"
  end
end

request_handler.join
response_handler.join

end
end

class MyServer < GServer
def initialize(port=10001, *args)
super(port, *args)
end
def serve(io)
ConnectionHandler.new(io)
end
end

Start the server

server = MyServer.new
server.audit = true
server.start

Here follows the client implementation:

socket = TCPSocket.new(‘localhost’, 10001)
cqueue = Queue.new
request_processor = Thread.new {
loop do
req = cqueue.pop
socket << req << “EOF
end
}

response_processor = Thread.new {
loop do
res = socket.gets(“EOF”).chomp(“EOF”)
puts “server response: #{res}”
cqueue << “enquiring minds want to know”
end
}

This message will start off the conversation

cqueue << “can i speak freely?”

server.join
request_processor.join
response_processor.join


#2

I am very sorry; I just realized that in the response_handler thread I
was writing to “socket” instead of “io”. I was actually just trying to
present a simplification of the problem I am having with my real
project. Arrgh! Now to go sift through all the lines of code to see if I
can get the real thing to work…