We have seen how to start a thread and different methods of managing them. Now, let's discuss how to share data between threads. One key feature of concurrency is its ability to share data between the threads in action. First, let's see what the problems associated with threads accessing common (shared) data are.
There won't be a problem if the data shared between threads is immutable (read-only), because the data read by one thread is unaffected by whether the other threads are reading the same data or not. The moment threads start modifying shared data is when problems begin to emerge.
For example, if the threads are accessing a common data structure, the invariants associated with the data structure are broken if an update is happening. In this case, the number of elements is stored in the data structure, which usually requires the modification of more than one value. Consider the delete operation of a self-balancing tree or a doubly linked list. If you don...