up:: Fundamentals of Operating Systems prev:: Chapter 15 – CPU Scheduling next:: Chapter 17 – I O Systems & Storage
Chapter 16 – Concurrency & Synchronization
Core idea
Concurrency introduces race conditions when shared data is accessed.
Problems
- Race condition – outcome depends on timing
- Critical section – code accessing shared state
- Deadlock – circular waiting
Synchronization tools
- Mutex – mutual exclusion
- Semaphore – counting access
- Spinlock – busy waiting
- Condition variable – waiting for state
Deadlock conditions
- Mutual exclusion
- Hold and wait
- No preemption
- Circular wait
Exam angles
- Concurrency bugs are hard to reproduce
- Deadlocks require all four conditions