Week 10 - July 15-19

Introduction

This week we are going to study message queues. We are then going to do a comparison between all four IPC methods studied so far (sockets, pipes, fifos and message queues).

Videos

Quiz

• Quiz 8 will be on message queues. Study chapter 46 of The Linux Programming Interface.

Lecture Material

• Message Queues - Chapter 46 of The Linux Programming Interface.
• Interprocess Communication Overview - Chapter 43 of The Linux Programming Interface.
• Comparing and Evaluating the Performance of Inter Process Communication Models in Linux Environment.

Labs

• Lab 7 - pipes between processes.
  
• Lab 8 - client/server with messaging.

Assignment(s)

Assignment 1.

Assignment 2.

Sample Code

Message Queues

• This week we study message queues. Code that demonstrates send/receive with message queues can be found at client.h, client1.cpp, client2.cpp with its Makefile.
• Code that demonstrates non-blocking message receive with message queues can be found at client.h, client1.cpp, client2.cpp with its Makefile.
• Code that demonstrates message send/receive with differing message types can be found at client.h, client3.cpp, client4.cpp with its Makefile.
• Code that demonstrates a complex structure for the message queue can be found at client.h, client1.cpp, client2.cpp with its Makefile.
• Finally, code that demonstrates the use of msgctl to retrieve message queue information can be found at client.h, client1.cpp, client2.cpp with its Makefile.

Inter-process communication, a comparison

• So far we have studied inter-process communication with pipes, fifos, sockets and messages. A comparison of their relative performance has been carried out. The performance parameter tested is the time to send 5 million messages of 26 characters each (the alphabet) from client to server or from one client to another. The test will show that there is very little difference in performance from one IPC to another.
  Code for testing the performance of fifos can be found at fifo1.cpp, fifo2.cpp with its Makefile.
  Code for testing the performance of pipes can be found at pipe.cpp with its Makefile.
  Code for testing the performance of message queues can be found at client1.cpp, client2.cpp with its Makefile.
  Code for testing the performance of unix stream sockets can be found at server.cpp, client.cpp with its Makefile.
  Code for testing the performance of inet datagram sockets can be found at msgServer.cpp, msgClient.cpp with its Makefile.
  If we increase the buffer sizes, both stream and datagram sockets are much faster. Code for testing the performance of unix stream sockets with large buffer sizes can be found at server.cpp, client.cpp with its Makefile.
  Code for testing the performance of inet datagram sockets with large buffer sizes can be found at msgServer.cpp, msgClient.cpp with its Makefile.
  
• See also the publication Comparing and Evaluating the Performance of Inter Process Communication Models in Linux Environment.