Handling Concurrency u0026 Deadlocks Quiz Quiz

Explore key concepts in handling concurrency and deadlocks with this challenging quiz. Evaluate your understanding of synchronization techniques, deadlock prevention, and best practices for managing concurrent operations in computing systems.

1. Identifying Deadlock Conditions

   Which of the following conditions must be present simultaneously for a deadlock to occur in a concurrent system?

   1. Preemption, infinite loop, atomicity, and mutual trust
   2. Sporadic access, busy waiting, mutual exclusion, and race condition
   3. Mutual exclusion, hold and wait, no preemption, and circular wait
   4. Starvation, hold and wait, preemption, and data inconsistency

   Explanation: Deadlock requires four necessary conditions: mutual exclusion, hold and wait, no preemption, and circular wait. These form the classic 'Coffman conditions' for deadlock. The other options include inaccurate or unrelated terms such as 'infinite loop,' 'mutual trust,' and 'sporadic access,' which are not formal deadlock conditions. While starvation and data inconsistency are problems in concurrency, they are different from deadlock specifics.

2. Critical Section Problem

   When multiple threads need to access a shared variable, what synchronization technique should be used to ensure safe concurrent access?

   1. Ignoring synchronization entirely
   2. Relying solely on thread priorities
   3. Using locks or mutexes
   4. Increasing the number of threads

   Explanation: Locks or mutexes are standard synchronization tools to ensure that only one thread accesses the critical section at a time, preventing race conditions. Ignoring synchronization exposes the code to data corruption. Relying on priorities does not guarantee mutual exclusion, and simply increasing thread count may escalate concurrency issues rather than solve them.

3. Deadlock Avoidance Strategy

   Which strategy can an operating system use to actively avoid deadlock by only granting resource requests that lead to a safe state?

   1. Static variable assignment
   2. Banker's algorithm
   3. Random scheduling
   4. Busy spinning

   Explanation: The Banker's algorithm is designed to prevent deadlock by examining whether granting a resource leaves the system in a safe state. Random scheduling does not account for safety, busy spinning wastes CPU without resolving resource contention, and static variable assignment is not a strategy for runtime resource allocation. Therefore, Banker's algorithm is the correct approach.

4. Starvation vs. Deadlock

   If a process waits indefinitely for a resource because other processes are repeatedly granted access instead, what concurrency problem is being described?

   1. Deadlock
   2. Starvation
   3. Data race
   4. Liveliness

   Explanation: Starvation occurs when a process is perpetually denied necessary resources, often because other processes continually preempt access. Deadlock refers to a situation where progress halts because each process holds a resource and waits for another, while a data race involves concurrent modifications without synchronization. 'Liveliness' is not a recognized concurrency problem, making 'starvation' the correct answer.

5. Ordering Locks to Prevent Deadlocks

   What is a commonly recommended practice for preventing deadlocks when multiple locks are needed by concurrent processes?

   1. Avoid using any synchronization at all
   2. Use random order for acquiring locks
   3. Release all locks before requesting new ones
   4. Always acquire locks in a consistent global order

   Explanation: Acquiring locks in a consistent order across all threads eliminates the possibility of circular wait, breaking one of the necessary deadlock conditions. Releasing all locks before requesting new ones can be inefficient and does not always address circular wait. Random acquisition increases unpredictability and potential deadlocks, while avoiding synchronization leads to unsafe data access and potential races.