Operating System Concepts Chapter 5.4

Producer-Consumer Problem

• A solution to the producer-consumer problem involves using an integer counter to keep track of the number of full buffers.
• The producer increments the counter after producing a new buffer, and the consumer decrements the counter after consuming a buffer.

Race Condition

• A race condition occurs when the execution of two or more processes overlaps, causing unexpected results.
• In the context of the producer-consumer problem, a race condition can occur when the producer and consumer access the shared counter simultaneously.

Critical Section Problem

• The critical section problem involves designing a protocol to allow multiple processes to access a shared resource without conflicts.
• Each process has a critical section of code that must be executed exclusively, ensuring that no other process can access the shared resource simultaneously.
• The critical section problem can be solved using a protocol that allows processes to request permission to enter the critical section and ensures that only one process can access the shared resource at a time.

Solution to Critical-Section Problem

• One solution to the critical-section problem involves using a shared variable turn to indicate which process can enter the critical section.
• Each process waits until turn equals its process number before entering the critical section.
• After finishing the critical section, the process sets turn to the next process number.

Solution using Test-and-Set()

• Another solution to the critical-section problem involves using a shared Boolean variable lock and the test_and_set() function.
• The test_and_set() function atomically sets lock to TRUE if it is FALSE, and returns the old value of lock.
• A process waits until lock is FALSE before entering the critical section, and sets lock to TRUE to prevent other processes from entering.

Semaphore

• A semaphore is a variable that can only be accessed using two indivisible operations: wait() and signal().
• wait() decrements the semaphore value, and if the value is negative, the process blocks.
• signal() increments the semaphore value, and if a process is blocked, it is awakened.

Deadlock and Starvation

• Deadlock occurs when two or more processes are waiting indefinitely for an event that can only be caused by one of the waiting processes.
• Starvation occurs when a process is indefinitely blocked due to a semaphore.
• Priority inversion is a scheduling problem that occurs when a lower-priority process holds a lock needed by a higher-priority process.

Classical Problems of Synchronization

• The bounded-buffer problem involves synchronizing access to a finite buffer by multiple producers and consumers.
• The readers-writers problem involves synchronizing access to a shared resource by multiple readers and writers.
• The dining-philosophers problem involves synchronizing access to a shared resource (chopsticks) by multiple philosophers.

Learn about the producer-consumer problem in operating systems, including the use of an integer counter to track full buffers. Understand how the producer and consumer interact with the buffer.