We’ve explored so much with our concurrency experiments and yet there’s one fundamental topic we haven’t touched so far. Deadlocks. Whenever we think of concurrency, we can’t help thinking of locks for protecting shared resources, managing synchronization and what not. But, as Uncle Ben has said, with great power comes great responsibility, similarly with great locks comes great deadlocks.
Picture the scenario: You’re on the phone with your friend, when suddenly he say ‘Hey! Hold on. I think I’m getting another call’ and before you can say anything, he puts you on hold. Now, you have no idea whether to hang up, or wait. Your friend could be coming back in 3 seconds or 3 hours you’ve no idea. Wouldn’t it be great if your phone service provided you a mechanism that whenever you’re put on hold, you can freely disconnect and whenever your friend disconnects the other call, you immediately get a ring. Let’s talk about managing synchronization between threads.
Love them or hate them, you just can not ignore singletons. Let’s try experimenting with singletons and concurrency.
In continuation with the last week’s experiment on protecting shared data in a concurrent system, let’s look at how we can make it work using C++ and threads.