Concurrency & Parallelism (Intro)

Q1. What is concurrency in programming?

1. A.Running only one task at a time sequentially
2. B.Handling multiple tasks in overlapping time periods✓ Correct
3. C.Exactly the same concept as true parallelism
4. D.Strictly sequential execution of all operations

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Q2. What is a thread?

1. A.A reusable function definition block
2. B.A type of string data structure
3. C.The smallest unit of execution within a process✓ Correct
4. D.A data structure for storing elements

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Q3. What is a race condition?

1. A.A debugging tool for analyzing multi-threaded applications
2. B.A bug where outcome depends on non-deterministic thread timing✓ Correct
3. C.A performance competition between different threads
4. D.A type of exception thrown during concurrent data access

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Q4. What is a process?

1. A.A function call that executes and then returns
2. B.An independent program with its own memory space✓ Correct
3. C.A variable that stores data during execution
4. D.The same thing as a thread in all respects

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Q5. What is the main benefit of concurrency?

1. A.Improved performance and responsiveness of programs✓ Correct
2. B.Simpler code that is easier to read and understand
3. C.Smaller program binaries with reduced memory footprint
4. D.Fewer bugs and errors during program execution overall

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Q6. What is multithreading?

1. A.A type of recursion with multiple recursive calls
2. B.Using multiple programming languages in one project
3. C.Using multiple processors in a distributed system
4. D.Running multiple threads within a single process✓ Correct

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Q7. What is the difference between concurrency and parallelism?

1. A.Concurrency always requires multiple CPU cores to function properly
2. B.Parallelism is always slower than concurrency in every scenario
3. C.They are exactly the same concept with no differences at all
4. D.Concurrency manages overlapping tasks; parallelism runs simultaneously✓ Correct

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Q8. What is a mutex?

1. A.An algorithm for sorting elements in a collection
2. B.A primitive data type for storing values
3. C.A lock ensuring exclusive resource access for one thread✓ Correct
4. D.A function for performing calculations on data values

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Q9. What is a deadlock?

1. A.A memory leak from unreleased dynamically allocated data
2. B.A type of infinite loop caused by incorrect conditions
3. C.Threads blocked forever waiting for each other resources✓ Correct
4. D.A program crash caused by a runtime error in code

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Q10. What is synchronization?

1. A.A file operation for reading and writing data safely
2. B.Running code statements in sequential order always
3. C.A network protocol for data transfer between systems
4. D.Coordinating shared resource access to prevent races✓ Correct

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Q11. What is the volatile keyword in Java?

1. A.A final variable that cannot be modified after assignment
2. B.A keyword ensuring reads always come from main memory✓ Correct
3. C.A variable that changes randomly without any cause
4. D.A type of exception thrown during concurrent operations

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Q12. What is async/await?

1. A.A type of loop for iterating over collection elements
2. B.A testing pattern for validating asynchronous behavior
3. C.A syntax for writing async code that looks synchronous✓ Correct
4. D.A threading model for managing parallel execution of tasks

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Q13. What is an atomic operation?

1. A.An indivisible operation completing without interruption✓ Correct
2. B.A nuclear physics operation on atomic particles
3. C.A file operation that reads and writes data to disk
4. D.A database transaction that groups multiple queries

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Q14. What is thread safety?

1. A.A testing concept for validating thread performance
2. B.Code functioning correctly under multi-thread access✓ Correct
3. C.A debugging feature for analyzing thread behavior
4. D.Threads that are guaranteed to never crash or fail

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Q15. What is context switching?

1. A.Saving one thread state and loading another for CPU switching✓ Correct
2. B.Changing the scope of a variable from local to global
3. C.Changing between different programming languages in a project
4. D.Switching between different source code files in an editor

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Q16. What is the dining philosophers problem?

1. A.A sorting problem for ordering elements in a collection
2. B.A classic problem illustrating resource allocation and deadlock✓ Correct
3. C.A database problem with concurrent transaction conflicts
4. D.A food-related algorithm for meal planning optimization

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Q17. What is the producer-consumer problem?

1. A.A database issue with concurrent read and write transaction conflicts
2. B.A business problem related to supply chain management
3. C.A network problem caused by packet loss during data transmission
4. D.A synchronization problem with shared buffer between producers and consumers✓ Correct

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Q18. What is a Future/Promise?

1. A.An object representing a value available in the future✓ Correct
2. B.A type of thread that executes tasks asynchronously
3. C.A variable that is declared for use at a later time
4. D.A timer that triggers a callback after a set delay

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Q19. What is the difference between optimistic and pessimistic concurrency control?

1. A.There is no meaningful difference between the two control approaches
2. B.Pessimistic concurrency control never uses any locks on resources
3. C.Optimistic concurrency control uses locks to prevent all conflicts
4. D.Optimistic assumes no conflicts and validates; pessimistic locks first✓ Correct

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Q20. What is a thread pool?

1. A.Pre-created worker threads reused for tasks✓ Correct
2. B.A memory pool for thread-local storage data
3. C.A collection of all threads in the system
4. D.A connection pool for database access threads

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Q21. What is a semaphore?

1. A.A counter-based primitive controlling shared resource access✓ Correct
2. B.A thread type for running background tasks in parallel
3. C.A simple flag variable for boolean state tracking
4. D.A type of lock for exclusive thread synchronization

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Q22. What is the Java Memory Model (JMM)?

1. A.A memory leak detector for finding unreleased allocations
2. B.A garbage collection model for reclaiming unused object memory
3. C.A specification defining thread memory interaction and visibility✓ Correct
4. D.How Java manages memory allocation for objects on the heap

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Q23. What is work stealing in thread pool implementations?

1. A.A security vulnerability where threads access unauthorized data
2. B.Interrupting running threads to reassign their execution priority
3. C.Idle threads stealing tasks from busy threads for load balancing✓ Correct
4. D.Taking another thread source code and executing it directly

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Q24. What is the Compare-and-Swap (CAS) operation?

1. A.A file swap operation for exchanging file contents
2. B.A string operation for replacing character subsequences
3. C.A sorting operation for ordering elements in arrays
4. D.An atomic operation comparing and swapping memory values✓ Correct

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Q25. What is lock-free programming?

1. A.A type of race condition caused by missing synchronization
2. B.Programming without any synchronization mechanisms at all
3. C.Single-threaded programming without any concurrent access
4. D.Using atomic operations instead of locks for thread progress✓ Correct

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Q26. What is the difference between green threads and OS threads?

1. A.Green threads are runtime-scheduled; OS threads are kernel-managed✓ Correct
2. B.Green threads are always faster than OS threads in every scenario
3. C.They are exactly the same with no meaningful differences at all
4. D.OS threads use less memory than green threads in all situations

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Q27. What is the happens-before relationship in concurrency?

1. A.A scheduling algorithm for determining thread execution priority
2. B.Simple chronological ordering of events by their timestamps
3. C.A debugging concept for tracing the order of function calls
4. D.A guarantee that writes by one action are visible to another✓ Correct

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Q28. What is a read-write lock (ReentrantReadWriteLock)?

1. A.A file lock for preventing concurrent file access
2. B.A database lock for serializing transaction execution
3. C.A lock allowing multiple readers but exclusive writers✓ Correct
4. D.A mutex variant supporting recursive lock acquisition

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Q29. What is a memory barrier/fence?

1. A.A hardware instruction enforcing memory operation ordering for CPUs✓ Correct
2. B.A memory protection boundary between user and kernel space
3. C.A memory limit restricting maximum allocation size for processes
4. D.A garbage collection trigger that starts when memory is low

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Q30. What is Software Transactional Memory (STM)?

1. A.A concurrency mechanism using transactions for shared memory with retry✓ Correct
2. B.A memory allocation strategy for managing heap memory efficiently
3. C.A thread scheduler for determining execution order of all threads
4. D.A relational database system for persistent data storage

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