Question UnityEngine.Pool -> ObjectPool doesn't do pooling

I know it sounds weird but it feels like using the new ObjectPool doesn't do what it is supposed to do.
I have the following code:

Code (CSharp):

1.     void Start() {
2.         PopulatePool();
3.     }
4.  
5.     void PopulatePool() {
6.         Debug.Log("Populate!");
7.         pool = new ObjectPool<GameObject>(
8.         () => {
9.             Debug.Log("Create");
10.             GameObject enemy = Instantiate(enemyPrefab);
11.             enemy.GetComponent<EnemyHealth>().SetPool(pool);
12.             enemy.GetComponent<EnemyMover>().SetPool(pool);
13.             return enemy;
14.         },
15.         (enemy) => {
16.             Debug.Log("Get");
17.             enemy.SetActive(true);
18.         },
19.         (enemy) => {
20.             enemy.SetActive(false);
21.             Debug.Log("Release");
22.         },
23.         (enemy) => Destroy(enemy),
24.         true, 10, 10);
25.     }

When I run the game the pool does nothing, it doesn't initiate the 10 objects at the start but I see in the console
"Populate!"

Ok so maybe somewhy (although it defeats the purpose of pooling) it only instantiate when using pool.Get() so I tried to do that

Code (CSharp):

1.     void Start() {
2.         PopulatePool();
3.         EnemySpawner();
4.     }
5.  
6.     void PopulatePool() {
7.         Debug.Log("Populate!");
8.         pool = new ObjectPool<GameObject>(
9.         () => {
10.             Debug.Log("Create");
11.             GameObject enemy = Instantiate(enemyPrefab);
12.             enemy.GetComponent<EnemyHealth>().SetPool(pool);
13.             enemy.GetComponent<EnemyMover>().SetPool(pool);
14.             return enemy;
15.         },
16.         (enemy) => {
17.             Debug.Log("Get");
18.             enemy.SetActive(true);
19.         },
20.         (enemy) => {
21.             enemy.SetActive(false);
22.             Debug.Log("Release");
23.         },
24.         (enemy) => Destroy(enemy),
25.         true, 10, 10);
26.     }
27.  
28.     void EnemySpawner() {
29.         IEnumerator main() {
30.             while (this.isActiveAndEnabled) {
31.                 Debug.Log($"{pool.CountAll}");
32.                 pool.Get();
33.                 yield return new WaitForSeconds(spawnDelay);
34.             }
35.         }
36.  
37.         StartCoroutine(main());
38.     }
39.  

Now each time I do a pool.Get(); it instantiate a new instance, but if I let it run for a while it never stops instantiating instances, the pool just keeps growing forever 1000,2000,3000 objects basically not acting like a pool at all.

I expected the pool to not increase above the max limit I gave it, this is what I see in the log (will copy from the middle cause it is never ending)

...

Create

Get

20

Create

Get

21

Create

Get

22

...

I disabled the releasing on purpose(enemy prefab doesn't do any destroy or release now) to first check why the pool doesn't behave like a pool, when I tried to release stuff it didn't help much it seems like released items are going back to the pool fine but still if I create quicker than I release then the pool just keeps expanding and issuing a create command each time I use Get instead of creating it all at the startup. (and also the scene has tons of objects because nothing ever gets destroyed even though I added in the pool the destroy callback)

I probably miss something here but not sure what
My pool variable looks like this if it matters:

ObjectPool<GameObject> pool;

 

Unity's pooling classes do not create objects by themselves, they will only fill up as you release objects and later return them again to be re-used. If you want to pre-warm the pool, you have to get and immediately release a given number of objects.

The argument you set in its constructor is

defaultCapacity

. It only sets the initial capacity of the list it creates to hold the objects, to avoid reallocating the backing array a couple of times when objects are added to the list. It does not mean that it creates that many objects.

 

Do you need pooling or are you just learning about it for fun?

The high costs and issues associated with object pooling / pools:

https://forum.unity.com/threads/object-pooling.1329729/#post-8405055

https://forum.unity.com/threads/object-pooling-in-a-tower-defense-game.1076897/#post-6945089

 

It was an exercise so I didn't really need them, what would you say is a valid use case for object pooling?

 

Hmm I see it explains some stuff, but why it does not honor the "maxSize" as well? objects are created infinitely I reached more than 1000 objects in the scene(in the pool) even though I set the maxSize to 10.

EDIT: ok I see once I stop spamming the pool with Get(), it actually started to destroy the excess (it stays at a number higher than defaultCount but close to it, and lower than maxSize), also all the counting of the pool like CountActive / CountAll seems really inaccurate I had to manually count the objects in the scene(that belongs to the pool).

 

The case where it might make a difference. Remember: it has an extremely high cost. Don't do it unless you must.

DO NOT OPTIMIZE "JUST BECAUSE..." If you don't have a problem, DO NOT OPTIMIZE!

If you DO have a problem, there is only ONE way to find out. Always start by using the profiler:

Window -> Analysis -> Profiler

Failure to use the profiler first means you're just guessing, making a mess of your code for no good reason.

Not only that but performance on platform A will likely be completely different than platform B. Test on the platform(s) that you care about, and test to the extent that it is worth your effort, and no more.

https://forum.unity.com/threads/is-...ng-square-roots-in-2021.1111063/#post-7148770

Remember that optimized code is ALWAYS harder to work with and more brittle, making subsequent feature development difficult or impossible, or incurring massive technical debt on future development.

Notes on optimizing UnityEngine.UI setups:

https://forum.unity.com/threads/how...form-data-into-an-array.1134520/#post-7289413

At a minimum you want to clearly understand what performance issues you are having:

- running too slowly?
- loading too slowly?
- using too much runtime memory?
- final bundle too large?
- too much network traffic?
- something else?

If you are unable to engage the profiler, then your next solution is gross guessing changes, such as "reimport all textures as 32x32 tiny textures" or "replace some complex 3D objects with cubes/capsules" to try and figure out what is bogging you down.

Each experiment you do may give you intel about what is causing the performance issue that you identified. More importantly let you eliminate candidates for optimization. For instance if you swap out your biggest textures with 32x32 stamps and you STILL have a problem, you may be able to eliminate textures as an issue and move onto something else.

This sort of speculative optimization assumes you're properly using source control so it takes one click to revert to the way your project was before if there is no improvement, while carefully making notes about what you have tried and more importantly what results it has had.

 

Get the free MasterObjectPooler from the store and stop worrying about the pool.