Intro to concurrency control

What is mutual exclusion in concurrency control?

• Ensures only one process accesses a critical section at a time.

• Prevents data corruption and conflicts.

What are common challenges with concurrent execution?

• Race conditions: Unsynchronized access affects results.

• Resource starvation: Processes wait indefinitely for resources.

• Deadlocks: Processes wait indefinitely for each other.

How does Dekker's algorithm achieve mutual exclusion?

• Uses turn-based system.

• Employs flags for each process to manage access.

What problems arose in early attempts of Dekker's algorithm?

• Processes wait indefinitely.

• Failed to ensure mutual exclusion.

• Potential deadlocks and livelocks.

How is mutual exclusion correctly implemented in Dekker's algorithm?

• Uses a flag array and a turn variable.

• Manages orderly access based on other processes' status.

What does Peterson's algorithm improve upon in mutual exclusion?

• Simplifies entry and exit from critical sections.

• Efficiently resolves deadlocks and race conditions.

What is a semaphore in concurrency control?

• Synchronization tool using integer values.

• Manages orderly resource access among processes.

What are the key operations of a semaphore and their functions?

• SemWait: Decrements semaphore; blocks process if negative.

• SemSignal: Increments semaphore; unblocks waiting process.

1. How do semaphores manage mutual exclusion?

• SemWait before entering critical section to ensure exclusivity.

• SemSignal after leaving to open access for others.

1. How does the Producer-Consumer problem use semaphores for synchronization?

• Synchronizes producers and consumers to prevent overwriting and empty data reads.

• Ensures producers don't add to a full buffer; consumers don't read from an empty one.