Sample Problems for Multithreading Practice

Question

I'm about to tackle what I see as a hard problem, I think. I need to multi-thread a pipeline of producers and consumers.

So I want to start small. What are some practice problems, in varying levels of difficulty, that would be good for multi-threading practice? (And not contrived, impractical examples you see in books not dedicated to concurrency).

What books or references would you recommend that focus on concurrency and give in-depth problems and cases?

(I'd rather not focus on the problem I want to solve. I just want to ask for good references and sample problems. This would be more useful to other users. I'm not stuck on the problem.)

Answer 1

Most text book problems, like readers-writers, producers-consumers or dinning philosophers are all illustrations of the mutex. I would prefer to model a prototype which is a simplistic approximation the bigger problem and go ahead.

I have some times seen situations where dead-lock avoidance is what is needed and dead-lock prevention measures are being used. It is always a good idea to analyse if Banker's algorithm would suit the case or not.

Answer 2

If you have enough time to invest I would recommend the book "Concurrency: State Models & Java Programs, 2nd Edition" by Jeff Magee and Jeff Kramer, John Wiley&Sons 2006

You can ignore the Java part if you are using some other language

There's a language used to model processes and concurrent processes called FSP. It needs some time and energy to be invested in order to be proficient in the language. There's a tool (LTSA, both are free and supported by an Eclipse plugin or stand alone app) which verifies your models and make you pretty shure that your model is correct from the standpoint of concurrent execution.

Translating this models to your language constructs is then just a question of programming technique and few design patterns.

Answer 3

I'm not sure what you are looking for. But in real world enterprise situation, we usually use some kind of messaging framework when doing producers consumers stuff. Tipically in Java, that's JMS. And you can use the excellent Spring Framework to help you along.

Answer 4

To be honest, many real-world multithreading programs are not doing much more than reading/writing some value (whether string or int) -- circular buffers (as a network connection might need), readers/writers of log files, etc.

In fact, I'd say that if you implement (or find) a solid (and generic) circular buffer, and then run all thread-to-thread communication through those buffers as the only contact point, that'll cover a very large portion of any multithread syncing you might need to do. (Unless you're working in a buzzword-compliant environment, and need to tack "enterprise", "messaging", or whatever onto the buzzword list... or you're writing a database or operating system.)

(Note that "circular buffer" is a fairly C-centric term, being rooted in the relatively direct manipulation of a block of memory. Python's Queue class implements the same basic principle in a list-centric way, and I'm sure that numerous other languages have conceptually similar constructs under slightly different names...)

Answer 5

If you're working with Java at all (and possibly even if you're not), you should definitely read Java Concurrency In Practice.

Answer 6

Completely ignoring your request, I'll suggest that you should look at SEDA (staged event driven architecture) as a way to think about setting up a multi-threaded pipeline of producers and consumers.

Answer 7

The little book of semaphores is a good free book. The author takes a unique approach of first asking a problem and then presenting hints before answering. The problems increase in difficulty level gradually, and the book isn't written for any language in particular but covers general multithreading concepts.