Simple Deadlock Examples
deadlock, language-agnostic, multithreading
Solution
Maybe a simple bank situation.
class Account {
double balance;
void withdraw(double amount){
balance -= amount;
}
void deposit(double amount){
balance += amount;
}
void transfer(Account from, Account to, double amount){
sync(from);
sync(to);
from.withdraw(amount);
to.deposit(amount);
release(to);
release(from);
}
}
Obviously, should there be two threads which attempt to run transfer(a, b) and transfer(b, a) at the same time, then a deadlock is going to occur because they try to acquire the resources in reverse order.
This code is also great for looking at solutions to the deadlock as well.
Problem
I would like to explain threading deadlocks to newbies. I have seen many examples for deadlocks in the past, some using code and some using illustrations (like the famous 4 cars). There are also classic easily-deadlocked problems like The Dining Philosophers, but these may be too complex for a real newbie to fully grasp. I'm looking for the simplest code example to illustrate what deadlocks are. The example should: - Relate to a "real" programming scenario that makes some sense - Be very short, simple and straight forward What do you recommend?