Bug #8442

sendmesg (blocking) of class BasicSocket is repeatably sent by the ruby kernel

Added by m_josenhans (Michael Josenhans) about 5 years ago. Updated 6 months ago.

Target version:
ruby -v:
ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-linux]



(1) The error occurs with the method "sendmesg" (blocking) of class BasicSocket on Ruby 2.0.0-p0 (rvm), but does not occur on Ruby 1.9.3-p392 (rvm).
(2) The error does not occur with the method "send" (non-blocking) of class BasicSocket on Ruby 1.9.3-p392 (rvm) and Ruby 2.0.0-p0 (rvm).

The bug can be reproduced with the code attached.

  • For (1) use the code as attached. The send message occurs at line 50 & 51.
  • For (2) comment out line 50 & 51 and uncomment line 52 & 53.

How to reproduce the error:


  • (({ruby halfsync_halfasync.rb}))

on second terminal (unix):

  • (({telnet localhost 10001}))

on Windows use telnet client e.g. putty and make sure to configure putty as passive ("Connection->Telnet->Telnet negotiation mode: Passive")

What the code does:
It implements the halfsync_halfasync design-pattern (see references in the code).

  • An (({EchoAcceptor})) is registered with the reactor to accept connection setup.
  • A thread pool is started waiting for tasks to be retrieved from a shared queue
  • Upon connection-setup of the telnet the (({EchoAcceptor})) is called and registers an (({EchoServerHandler})) with the Reactor to handle data received via the connection from the telnet client.
  • Upon reception of data via the telent connection, the (({EchoServerHandler})) assembles data until a newline (\n or \r\n) is received. When that is received, the whole line is put into the shared queue.
  • The first thread from the thread pool waiting grabs the received data and the socket from the shared queue and in line 50/51 adds the thread-ID, the number of messages handled by that thread and sends it as a reply to the sender using the received socket.

What to expect as output:

  • Upon entering e.g. text "!1234" and pressing return On Ruby 1.9.3-p392 on Linux:
  • See the as response the thread ID, the number of messages within the thread and the text.

On Ruby 2.0.0-p0 on Linux:

  • See same as with Ruby 1.9.3-p392 , but when pressing very fast return after entering no text, the message of thread-id and number of messages sent will be repeatedly received by the server.
  • As the number of messages is not increased with each sending, it will be repeatedly sent by the ruby kernel (c-code)

On Ruby 2.0.0-p0 on Windows:

  • Nothing is is sent back to the the telnet server, despite the fact that the message had been received at the servers of the thread pool.

  • Everything works file, if instead of blocking send (line 50/51) the non-blocking send (line 52/53) is used. However correct implementation of the halfsync-halfasync pattern, requires reasonably the usage of blocking "send" in thread pool.

I have to apologize that the program to reproduce the error is slightly large and complicated, but I believe that there is value, when ruby is able to run well known design patterns correctly.

The code does not run with ruby 1.8.7 and Jruby and Rubinius.

halfsync_halfasync.rb (9.86 KB) halfsync_halfasync.rb m_josenhans (Michael Josenhans), 05/24/2013 06:18 AM


#2 Updated by naruse (Yui NARUSE) 6 months ago

  • Target version deleted (2.6)

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