MCQs on Memory Management and Performance Optimization | Lua

Garbage Collection in Lua

1. What is the primary function of the garbage collector in Lua?
   • A) Free memory for unused variables
   • B) Automatically optimize code execution
   • C) Debugging errors in scripts
   • D) Monitor variable declarations
2. Which Lua function manually triggers garbage collection?
   • A) collectgarbage()
   • B) gccollect()
   • C) garbageCollect()
   • D) collectMemory()
3. What is the default behavior of Lua’s garbage collector?
   • A) It runs every time the script ends
   • B) It runs periodically based on memory usage
   • C) It runs only at user request
   • D) It never runs automatically
4. In Lua, which type of garbage collection algorithm is used by default?
   • A) Reference counting
   • B) Tracing garbage collection
   • C) Mark and sweep
   • D) Copying garbage collection
5. Which of the following Lua functions can be used to check the status of garbage collection?
   • A) collectstatus()
   • B) collectinfo()
   • C) collectgarbage("count")
   • D) gcstatus()
6. What happens if the Lua garbage collector is disabled?
   • A) Memory leaks may occur
   • B) The script runs faster
   • C) Variables are automatically destroyed
   • D) Errors will stop the program
7. What can you do to trigger a manual garbage collection cycle in Lua?
   • A) Call collectgarbage("collect")
   • B) Use collectgarbage("stop")
   • C) Use collectgarbage("pause")
   • D) None of the above
8. Which command is used to set the maximum heap size for Lua’s garbage collector?
   • A) collectgarbage("maxheap", size)
   • B) collectgarbage("setheap", size)
   • C) collectgarbage("setmax", size)
   • D) collectgarbage("setpause", size)
9. What does collectgarbage("setpause", value) do?
   • A) Sets how often the garbage collector will run
   • B) Defines when memory is freed
   • C) Sets the maximum memory threshold
   • D) Pauses garbage collection completely
10. Which of the following is a common drawback of using Lua’s automatic garbage collection?
    • A) It may cause performance issues due to unpredictability
    • B) It leads to memory fragmentation
    • C) It requires manual memory management
    • D) It cannot handle circular references

Profiling and Optimizing Scripts

11. What is the purpose of profiling in Lua?
    • A) To detect memory leaks
    • B) To measure and improve the performance of code
    • C) To optimize the appearance of the script
    • D) To compress the Lua bytecode
12. Which Lua function can be used to obtain performance statistics during script execution?
    • A) debug.trace()
    • B) debug.profile()
    • C) debug.getinfo()
    • D) os.time()
13. What is the role of os.clock() in Lua performance profiling?
    • A) Measures real-time elapsed since script start
    • B) Tracks memory usage over time
    • C) Measures CPU time used by the script
    • D) Returns the current system time
14. What is the purpose of Lua’s require function in performance optimization?
    • A) To load libraries only when necessary
    • B) To automatically clean up memory
    • C) To improve the readability of code
    • D) To handle user input more efficiently
15. Which Lua feature can help reduce the memory overhead in a script?
    • A) Using global variables
    • B) Using tables to store data efficiently
    • C) Reducing the number of loops
    • D) Avoiding local variables
16. Which of the following tools can be used to profile Lua scripts?
    • A) LuaProf
    • B) LuaDebugger
    • C) LuaProfiler
    • D) None of the above
17. What is the purpose of using the debug library in Lua?
    • A) To handle errors in a script
    • B) To profile and inspect code execution
    • C) To optimize garbage collection
    • D) To format strings efficiently
18. How can you reduce the number of garbage collection cycles in Lua?
    • A) Use fewer tables in the script
    • B) Avoid creating new objects during execution
    • C) Force garbage collection to occur more often
    • D) Increase the number of local variables
19. What is a major drawback of using tables as an optimization strategy in Lua?
    • A) Tables increase memory usage due to garbage collection overhead
    • B) Tables cause excessive CPU usage
    • C) Tables require extra code to manage memory manually
    • D) Tables slow down script execution in all cases
20. Which of the following techniques can help to reduce Lua script execution time?
    • A) Writing shorter code
    • B) Avoiding complex loops and recursion
    • C) Using more global variables
    • D) Calling collectgarbage() frequently

Avoiding Common Performance Pitfalls

21. What is a common performance issue when working with large tables in Lua?
    • A) Excessive use of memory due to table copying
    • B) High CPU usage due to inefficient looping
    • C) Garbage collection overhead due to object creation
    • D) Increased latency due to global variable access
22. Which of the following actions can cause Lua to suffer from memory fragmentation?
    • A) Allocating and deallocating memory frequently
    • B) Using local variables instead of global ones
    • C) Calling functions less frequently
    • D) Repeated use of collectgarbage()
23. What is the impact of using global variables excessively in Lua?
    • A) They can slow down the execution speed due to lookup time
    • B) They decrease memory consumption
    • C) They simplify the debugging process
    • D) They increase code readability
24. Which of the following is an efficient approach to table manipulation in Lua?
    • A) Using table.insert within a loop
    • B) Using table.remove for large tables
    • C) Pre-allocating the table with a fixed size when possible
    • D) Using tables for all variable types
25. How can you reduce the overhead of creating tables within loops in Lua?
    • A) Create a new table before each iteration
    • B) Reuse tables outside of the loop
    • C) Use global variables instead of tables
    • D) Avoid using tables in loops entirely
26. What is a potential performance pitfall when using the string concatenation operator (..) in Lua?
    • A) It uses excessive CPU time when concatenating large strings
    • B) It causes memory leaks in every concatenation
    • C) It decreases the efficiency of garbage collection
    • D) It reduces the readability of the code
27. Which technique helps minimize the impact of table resizing on performance?
    • A) Avoid resizing tables altogether
    • B) Resize tables frequently during script execution
    • C) Pre-allocate table size or use table size hints
    • D) Use only fixed-size tables
28. What is the most common cause of memory leaks in Lua?
    • A) Not freeing tables from memory after use
    • B) Too many variables in a global scope
    • C) Not using coroutines properly
    • D) Excessive function calls
29. What is one way to improve the performance of recursive functions in Lua?
    • A) Avoid using global variables in recursion
    • B) Convert recursion into an iterative solution
    • C) Increase the stack size
    • D) Call collectgarbage() before each recursion
30. What is a good practice when optimizing a Lua script for better performance?
    • A) Profile the script first, then address performance issues
    • B) Always use global variables for faster lookup
    • C) Avoid using tables for data storage
    • D) Write code without considering optimization

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