Read Write Lock
Explore how to design and implement a read write lock in Python that permits multiple readers to access shared data simultaneously while ensuring exclusive access for a single writer. Understand the synchronization using condition variables, managing reader counts, and preventing race conditions in concurrent environments.
We'll cover the following...
Read Write Lock
Imagine you have an application where you have multiple readers and a single writer. You are asked to design a lock which lets multiple readers read at the same time, but only one writer write at a time.
Solution
First of all let us define the APIs our class will expose. We'll need two for writer and two for reader. These are:
- acquire_read_lock
- release_read_lock
- acquire_write_lock
- release_write_lock
This problem becomes simple if you think about each case:
Before we allow a reader to enter the critical section, we need to make sure that there's no writer in progress. It is ok to have other readers in the critical section since they aren't making any modifications.
Before we allow a writer to enter the critical section, we need to make sure that there's no reader or writer in the critical section.
Let's start with the reader use case. We can have multiple readers acquire the read lock and to keep track of all of them; we'll need a count. We increment this ...