MCQs on Java Performance Optimization | Enhancing Java Application Efficiency
Java Performance Optimization MCQs: Enhancing Java Application Efficiency
Master the fundamentals of Java performance optimization with these 30 MCQs. Dive into memory management, garbage collection, profiling, JVM tuning, and multi-threaded application optimization. Improve your Java application efficiency by understanding core optimization techniques.
MCQs
1. Which part of the JVM is responsible for managing memory allocation and deallocation?
- A. Class Loader
- B. Garbage Collector
- C. Just-In-Time Compiler
- D. Memory Manager
2. In Java, which of the following is a primary goal of garbage collection?
- A. Increase CPU usage
- B. Free up heap memory
- C. Reduce application size
- D. Improve file handling
3. What does the term “heap memory” refer to in Java?
- A. The memory for stack operations
- B. Memory used for class loading
- C. Memory for dynamic allocation of objects
- D. Memory used for garbage collection only
4. Which garbage collection algorithm is specifically designed to reduce latency in Java?
- A. Serial GC
- B. CMS (Concurrent Mark-Sweep)
- C. G1 (Garbage First)
- D. Parallel GC
5. Which JVM option is used to specify the maximum heap size?
- A. -Xms
- B. -Xmx
- C. -Xmn
- D. -Xss
6. What is the purpose of the JVisualVM tool in Java?
- A. To debug syntax errors
- B. To compile Java code
- C. To profile applications and monitor JVM
- D. To optimize bytecode execution
7. Which of the following is used to perform memory profiling in Java applications?
- A. JVM
- B. JIT Compiler
- C. JConsole
- D. Memory Profiler
8. Which memory space stores objects that are short-lived and eligible for garbage collection soon after creation?
- A. Eden Space
- B. Old Generation
- C. Permanent Generation
- D. Stack Memory
9. What does the jstat tool primarily monitor?
- A. CPU usage
- B. Heap memory usage and garbage collection statistics
- C. Network latency
- D. Input/Output operations
10. Which JVM tuning flag is used to set the initial heap size in Java?
- A. -Xms
- B. -Xmx
- C. -XX
- D. -XX
11. Which Java tool is often used to monitor live threads and memory usage?
- A. JUnit
- B. JConsole
- C. JProfiler
- D. Maven
12. Which garbage collector is considered ideal for applications that require low pause times?
- A. G1 GC
- B. Parallel GC
- C. Serial GC
- D. ZGC
13. What is the purpose of the jmap command?
- A. To display heap memory usage details
- B. To monitor file I/O
- C. To compile Java code
- D. To display CPU usage
14. How does the Just-In-Time (JIT) compiler help in improving performance?
- A. By performing garbage collection
- B. By compiling code at runtime to native code
- C. By increasing heap size
- D. By optimizing stack memory
15. What is “thread contention” in the context of multi-threaded applications?
- A. Multiple threads completing tasks without synchronization
- B. The process where threads compete for shared resources
- C. Thread execution in sequential order
- D. Running threads in isolation
16. Which JVM option allows you to enable parallel garbage collection?
- A. -XX:+UseParallelGC
- B. -XX:+UseSerialGC
- C. -XX:+UseG1GC
- D. -XX:+UseZGC
17. In Java, which tool is commonly used for profiling CPU and memory usage in a production environment?
- A. Eclipse
- B. JProfiler
- C. JUnit
- D. NetBeans
18. Which type of garbage collection is specifically designed for applications that allocate and deallocate a large number of short-lived objects?
- A. Serial GC
- B. CMS GC
- C. G1 GC
- D. Scavenge GC
19. What is the primary purpose of the jstack command?
- A. To capture memory snapshots
- B. To print stack traces of threads
- C. To measure heap usage
- D. To monitor CPU performance
20. What is the impact of excessive garbage collection in a Java application?
- A. Decreased memory usage
- B. Increased application performance
- C. Increased application latency due to frequent pauses
- D. Reduced CPU usage
21. Which of the following techniques is used to reduce memory fragmentation in Java?
- A. Memory allocation
- B. Defragmentation
- C. Compaction
- D. Memory splitting
22. In Java NIO, which buffer type is recommended to enhance performance with large I/O operations?
- A. ByteBuffer
- B. FileBuffer
- C. CharBuffer
- D. MemoryBuffer
23. Which garbage collection algorithm is used by default in Java 8?
- A. CMS
- B. G1 GC
- C. Serial GC
- D. Parallel GC
24. Which of the following allows Java to efficiently manage memory for multi-threaded applications?
- A. Object Pooling
- B. Thread Local Storage
- C. Shared Memory
- D. Thread Serialization
25. What is the purpose of the -XX:+UseConcMarkSweepGC flag?
- A. To enable concurrent garbage collection
- B. To increase the maximum heap size
- C. To reduce thread count
- D. To disable garbage collection
26. How does the WeakReference class in Java help in memory management?
- A. It holds references that allow garbage collection when memory is needed
- B. It prevents garbage collection
- C. It optimizes CPU performance
- D. It helps in profiling memory
27. Which type of thread pool is recommended for CPU-intensive tasks to maximize efficiency?
- A. Fixed Thread Pool
- B. Cached Thread Pool
- C. Scheduled Thread Pool
- D. Single Thread Pool
28. In Java, how does memory leak occur?
- A. By releasing unused memory
- B. By not releasing memory occupied by unreachable objects
- C. By allocating memory to stack
- D. By allocating memory to static fields
29. What is “lock contention” in the context of optimizing multi-threaded applications?
- A. Multiple threads are locked in a loop
- B. Multiple threads trying to acquire the same lock
- C. A single thread acquiring multiple locks
- D. No threads attempting to acquire any lock
30. Which of the following strategies can improve Java application performance in multi-threaded scenarios?
- A. Increasing memory allocation
- B. Reducing the number of synchronized methods
- C. Using single-threaded execution
- D. Increasing thread sleep time
Answer Key
| QNo | Answer |
|---|---|
| 1 | B. Garbage Collector |
| 2 | B. Free up heap memory |
| 3 | C. Memory for dynamic allocation of objects |
| 4 | B. CMS (Concurrent Mark-Sweep) |
| 5 | B. -Xmx |
| 6 | C. To profile applications and monitor JVM |
| 7 | D. Memory Profiler |
| 8 | A. Eden Space |
| 9 | B. Heap memory usage and garbage collection statistics |
| 10 | A. -Xms |
| 11 | B. JConsole |
| 12 | D. ZGC |
| 13 | A. To display heap memory usage details |
| 14 | B. By compiling code at runtime to native code |
| 15 | B. The process where threads compete for shared resources |
| 16 | A. -XX:+UseParallelGC |
| 17 | B. JProfiler |
| 18 | D. Scavenge GC |
| 19 | B. To print stack traces of threads |
| 20 | C. Increased application latency due to frequent pauses |
| 21 | C. Compaction |
| 22 | A. ByteBuffer |
| 23 | D. Parallel GC |
| 24 | B. Thread Local Storage |
| 25 | A. To enable concurrent garbage collection |
| 26 | A. It holds references that allow garbage collection when memory is needed |
| 27 | A. Fixed Thread Pool |
| 28 | B. By not releasing memory occupied by unreachable objects |
| 29 | B. Multiple threads trying to acquire the same lock |
| 30 | B. Reducing the number of synchronized methods |