Garbage collector
- Game Development course
- Expert
- Lesson 7/47
- 4 min
Learn how the C# GC works and the cost of allocation.
What is the garbage collector?
In a C# program the memory of objects that are no longer used is reclaimed automatically. The structure that does this is called the garbage collector (GC). When an object has no references left, the GC can clean it up.
Nesne kasa = new Nesne(); // allocation
kasa = null; // no reference left
// the GC can clean this objectThanks to the GC there is no need to free memory by hand.
The cost of allocation
Creating a new object means reserving memory, that is, an allocation. Every allocation raises the chance of the GC running, and small hiccups can happen at collection time. This is why producing new objects every frame is avoided.
void Update()
{
// an allocation every frame raises GC pressure
int[] dizi = new int[8];
}A game with fewer allocations runs smoother.
Practice Keep an allocation counter
In a class named BellekTakibi, define a string field named islem with the value "Tahsis" and an integer field named nesneSayisi with the value 3. In the Start method increase nesneSayisi by two and print the text "Toplam nesne: " joined with nesneSayisi using Debug.Log.
Starter code
using UnityEngine;
public class BellekTakibi : MonoBehaviour
{
// islem adli metin alanini "Tahsis", nesneSayisi adli tam sayi alanini 3 degeriyle tanimla
void Start()
{
// nesneSayisi degerini iki artir
// "Toplam nesne: " + nesneSayisi biciminde yazdir
}
}Sample solution
using UnityEngine;
public class BellekTakibi : MonoBehaviour
{
string islem = "Tahsis";
int nesneSayisi = 3;
void Start()
{
nesneSayisi = nesneSayisi + 2;
Debug.Log("Toplam nesne: " + nesneSayisi);
}
}Expected output
Toplam nesne: 5
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 When can an object be cleaned by the GC?
- Automatically in every frame
- When the script is compiled
- When the GameObject is added to the scene
- When it has no references left Correct answer
Explanation: The GC only cleans objects that no longer have any references; it does not touch reachable objects.
2 Trigger a GC collection manually
System.____.Collect(); System.GC.Collect();Explanation: The GC class lives inside the System namespace; System.GC.Collect() can trigger a collection manually.
3 GC terms
| Term | Meaning |
|---|---|
GC (Garbage Collector) |
The structure that reclaims memory |
Tahsis |
Reserving memory for a new object |
Summing |
The cleanup pass of the GC |
Referans |
The link that points to an object |