garbage collection

Question 1

What is garbage collection in C#?

Answer 1

• Automatic memory management process
• Identifies and reclaims memory that is no longer used by the program

Question 2

Explain how garbage collection works in C#

Answer 2

• Garbage collector runs in background
• Identifies objects that are no longer reachable from the application’s root (local variables, static variables) and reclaims their memory

Question 3

Garbage collection generations - Gen0

Answer 3

• Newly created objects
• Designed for short-lived objects that are expected to be collected quickly
• Objects in Gen0 are collected frequently

Question 4

Garbage collection generations - Gen1

Answer 4

• Objects that survive Gen0 collection are promoted to Gen1
• These objects have longer lifespan than Gen0 but are still relatively short-lived

Question 5

Garbage collection generations - Gen2

Answer 5

• Objects that survive multiple Gen1 collections are promoted to Gen2
• Long-lived objects
• Collections here are less frequent

Question 6

Garbage collection process

Answer 6

Marking

Garbage collector identifies which objects can be cleaned and marks the live objects

Sweeping

Garbage collector reclaims the memory occupied by objects that are marked as live

Compacting

Objects that survive Gen0 are promoted to Gen1, etc.

Question 7

What is the purpose of the System.GC class in C#?

Answer 7

• Provides methods and properties for interacting with garbage collector
• Allows developers to request garbage collection, etc.

Question 8

What is the difference between managed and unmanaged resources in the context of garbage collection?

Answer 8

Managed resources

Objects under control of .NET runtime

Subject to garbage collection

Unmanaged resources

External resources such as database connections

Require explicit cleanup

Question 9

How can you force garbage collection in C#?

Answer 9

• Calling the System.GC.Collect method
• Not recommended because it can disrupt the natural behavior of the garbage collector

Question 10

What are memory leaks, and how can you avoid them in C#?

Answer 10

• Occurs when objects are not properly released
• Causing memory consumption to grow indefinitely

To avoid:

• ensure that objects are properly disposed of
• especially unmanaged resources by using IDisposable or the ‘using’ statement

Question 11

Explain the concept of the “root” in garbage collection.

Answer 11

• Set of references that are directly accessible from the program
• Includes local variables, static variables, and references from active threads

Question 12

What is the impact of garbage collection on application performance?

Answer 12

• Temporary pauses can occur called “garbage collection pauses”

Question 13

What are weak references in C#, and when are they useful?

Answer 13

• They indicate objects that can be garbage collected even if they have references