Restart Scene causes Leaks. Help please

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Restart Scene causes Leaks. Help please

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Started 3 months ago by goodeats2009
Latest reply from goodeats2009

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goodeats2009
Member

hi, can you advise me on how to properly restart a scene? when i first start the scene, everything is ok but for example i completed the scene and run it again, i get all these leaks:

Leaked Object	#	Address	Size	Responsible Library	Responsible Frame
Malloc 2.50 KB,1	0x7a13e00	2.50 KB	Versus	-[CCTextureAtlas resizeCapacity:]
Malloc 16 Bytes,1	0x11cdc950	16 Bytes	Versus	ccArrayNew
CCArray,1	0x11cb42e0	16 Bytes	Versus	-[CCSpriteBatchNode initWithTexture:capacity:]
CCArray,1	0x11cd2270	16 Bytes	Versus	-[CCSpriteBatchNode initWithTexture:capacity:]
Malloc 224 Bytes,1	0x11cb0780	224 Bytes	Versus	ccArrayNew
Malloc 224 Bytes,1	0x11cd2190	224 Bytes	Versus	ccArrayNew
CCTMXLayer,1	0x11cb4750	320 Bytes	Versus	+[CCTMXLayer layerWithTilesetInfo:layerInfo:mapInfo:]
NSMutableDictionary,1	0x11cb08f0	48 Bytes	Versus	-[CCTMXLayer initWithTilesetInfo:layerInfo:mapInfo:]
Malloc 16 Bytes,1	0x11cae090	16 Bytes	Versus	ccCArrayNew
CCTMXTilesetInfo,1	0x11cae360	48 Bytes	Versus	-[CCTMXMapInfo parser:didStartElement:namespaceURI:qualifiedName:attributes:]
Malloc 1.00 KB,1	0xaa17c00	1.00 KB	Versus	ccCArrayNew
Malloc 1.00 KB,1	0xaa01000	1.00 KB	Versus	inflateMemoryWithHint
__NSCFString,2	< multiple >	64 Bytes	Foundation	-[NSPlaceholderString initWithBytes:length:encoding:]
CCSprite,1	0x11cd2590	432 Bytes	Versus	-[CCTMXLayer appendTileForGID:at:]
CCTextureAtlas,1	0x11cb4330	48 Bytes	Versus	-[CCSpriteBatchNode initWithTexture:capacity:]
Malloc 16 Bytes,1	0x11cae060	16 Bytes	Versus	ccArrayNew

i am using a game manager to replace scenes.

-(void) runSceneWithID:(SceneTypes)sceneID {
    SceneTypes oldScene = currentScene;
    currentScene = sceneID;
    id sceneToRun = nil;
    switch (sceneID) {
        case kIntroScene:
            sceneToRun = [IntroScene node];
            break;

        case kMainMenuScene:
            sceneToRun = [MainMenuScene node];
            break;
        case kLevelSelectScene:
            sceneToRun = [LevelSelectScene node];
            break;
        case kLevelCompleteScene:
            sceneToRun = [LevelCompleteScene node];
            break;
        case kGameLevel1:
            curLevel = kGameLevel1;
            sceneToRun = [TowerSelectLayer node];
            break;
        case kGameLevel2:
            curLevel = kGameLevel2;
            sceneToRun = [TowerSelectLayer node];
            break;
        case kGameLevel3:
            curLevel = kGameLevel3;
            sceneToRun = [TowerSelectLayer node];
            break;
        case kGameLevel4:
            curLevel = kGameLevel4;
            sceneToRun = [TowerSelectLayer node];
            break;
        case kGameLevel5:
            curLevel = kGameLevel5;
            sceneToRun = [TowerSelectLayer node];
            break;

        default:
            CCLOG(@"Unknown ID, cannot switch scenes");
            break;
    }
    if (sceneToRun == nil) {
        currentScene = oldScene;
        return;
    }

    if ([[CCDirector sharedDirector] runningScene] == nil) {
        [[CCDirector sharedDirector] runWithScene:sceneToRun];
    } else {
        [[CCDirector sharedDirector] replaceScene:sceneToRun];
    }
}

although its a game manager, it actually restarts the same scene every each time. in the maingamelayer i use a switch to determine which level is selected

curGameLevel = [GameManager sharedGameManager].curLevel;
        switch (curGameLevel) {
            case kGameLevel1:
                break;
            case kGameLevel2:
                break;
            case kGameLevel3:
                [self schedule:@selector(addEnergyCube) interval:25.0];
                break;
            case kGameLevel4:
                [self schedule:@selector(addEnergyCube) interval:25.0];
                break;
            case kGameLevel5:
                [self schedule:@selector(addEnergyCube) interval:25.0];
                break;
            default:
                break;
        }

also in the maingamelayer, i try to clear all the arrays that where used in the run of the scene

-(void) cleanScene {

    DataModel *m = [DataModel getModel];
    [m._towers removeAllObjects];
    [m._towersR0 removeAllObjects];
    [m._towersR1 removeAllObjects];
    [m._towersR2 removeAllObjects];
    [m._towersR3 removeAllObjects];
    [m._towersR4 removeAllObjects];
    [m._towersR5 removeAllObjects];
    [m._towersR6 removeAllObjects];
    [m._towersR7 removeAllObjects];
    [m._towersR8 removeAllObjects];
    [m._towersR9 removeAllObjects];
    [m._targets removeAllObjects];
    [m._targetsR0 removeAllObjects];
    [m._targetsR1 removeAllObjects];
    [m._targetsR2 removeAllObjects];
    [m._targetsR3 removeAllObjects];
    [m._targetsR4 removeAllObjects];
    [m._targetsR5 removeAllObjects];
    [m._targetsR6 removeAllObjects];
    [m._targetsR7 removeAllObjects];
    [m._targetsR8 removeAllObjects];
    [m._targetsR9 removeAllObjects];
}

i am not sure if this the right way to delete all objects in the arrays.
please help. i don't if its not dealloc correctly or what, i don't know. thank you.

Posted 3 months ago #

Birkemose
Moderator
You must be missing something in dealloc of your scene.
How you release your arrays, depends a bit on what you put into them. If you added obj-c id's only, there should be no need to remove the objects manually, you just have to release it
```
[ m._towers release ];
```
If m._towers reached a retain count of 0, it will call its own dealloc, which should release all contained objects, remove them from the list, and release the memory associated with the array.
Posted 3 months ago #
goodeats2009
Member

Hi, the arrays still contain class objects when the scenes end, like plants vs zombies, when you win the level you still have the plants in the scene when u complete the level. I'm removing them onEnter [super onEnter] to clear out the arrays just like the very first time you ran the game. U see the very first time the game runs, there is no leak. But the second time it starts leaking all those things. How do u properly restart a scene like it never ran before? Thanks

Posted 3 months ago #
Birkemose
Moderator

I dont think you should switch scene in the first place, if the new scene is the same as the old scene. In that case you would be better of implementing a reset method or something.
You should not remove them in onEnter. If anything, you should remove them in dealloc.

Posted 3 months ago #
goodeats2009
Member

Hi, sorry, I probably miswrote something there. The game flows like this
LevelSelectScene -> TowerSelectScene -> gameplayScene. So everytime the gameplayScene is done, it goes through the whole loop again. Does that count as replacing a scene? Those scenes are all the same though, only difference is more options can be selected depending on the level selected which is handled by switch statement. Tnx

Posted 3 months ago #
Birkemose
Moderator

Memory wise it doesn't matter if it is the same scene or not. What matters is, that when you replace a scene, you must make sure that it is completely wiped from memory, otherwise you will get leaks. Only exception is if you push a scene. In that case it is kept in memory, and must be popped back later.

Posted 3 months ago #
goodeats2009
Member

Is there a check that I can do to make sure that the scene is completely wiped from memory? Looks like that is what's happening since if I run it the first time, there is nothing in the memory yet hence so leaks show up. I do want to use replaceScene instead of pushScene. So like in my flowchart:

LevelselectScene gets replaced by towerselectScene, then gets replaced by maingameScene, then replaced by levelCompletedScene, then goes back to levelselectScene and process starts all over again.

The maingameScene is the heart of the game, everything happens there and is the scene I need to clear everything(arrays, etc) when it starts. Thanks so much

Posted 3 months ago #
Karl
Member

It looks like you're leaking CCTMXLayer objects. Look for any place you're using that and make sure you're not doing a retain or alloc/init without a corresponding release.
Any time you replace a scene, the old one gets released. The only way something can leak is if you're not managing your retains and releases properly somewhere in your scene's child objects (or if you're causing retain cycles by using blocks incorrectly).
Have you run your code through the analyzer?

Reloading a new copy of the current scene is safer than trying to "clean" an existing scene (less chance to introduce bugs).
You should probably encapsulate the concept of "clearing" your data model. Outside objects shouldn't be modifying internal stuff directly. If you don't need to persist the model data across sessions, just delete and recreate the model.

Stay simple until you get a bottleneck.

Posted 3 months ago #
goodeats2009
Member

Hi Karl, when I start the scene the first time, those leaks don't show up, when I get to the next level or go to any other level after that is when those leaks show up. Reloading a new copy of the scene is exactly what I want to happen. I just dont know how to do it. How do u do that?what I want is after a level is completed either the player succeeds or failed, to just wipe out the scene and start again like it ran the very first time. Tnx

Posted 3 months ago #
Karl
Member
Yeah, the leaks won't show up when you load the scene the first time because the leaks are IN your scene somewhere. Something you're creating/retaining inside your scene class is not getting released when that scene gets destroyed.

The leaks you see when loading the scene a second time are leaked objects from the PREVIOUSLY loaded scene. From the list you gave at the start, I don't see any CCScene objects, so I doubt the entire scene is leaking. You need to check inside your scene class to make sure it's not leaking any objects that it manages.

As for reloading a new copy of a running scene, a quick way to do it is like this:
```
CCScene* newScene = [[[[CCDirector sharedDirector] runningScene] class] node];
[[CCDirector sharedDirector] replaceScene:newScene];
```
Posted 3 months ago #
goodeats2009
Member

So if I have NSMutableArrays that have objects in them. When I replace the scene, do the objects inside those arrays get destroyed also without me having to remove them manually? I have a gamemanager which I showed above, does that do the job of replacing the scene or is my code wrong?

Posted 3 months ago #
Karl
Member

It's difficult to say from the code above, but you absolutely need to have a rock solid understanding of memory management in Objective-C before you can debug this issue properly.

The Apple docs on memory management are top notch quality. I definitely recommend going through all of them before tackling this further:

https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/Articles/MemoryMgmt.html

Posted 3 months ago #
goodeats2009
Member

Hi, u are totally right, I will read through it and do my code aaun tonight. I'll let u know what I find out. Tnx a lot.

Posted 3 months ago #
goodeats2009
Member

hey Birkmose and Karl, thanks both for the advice, Karl that documentation helped me a lot. i was leaking the tile map and was able to fix it. and obviously it was my own mistake, mixing the accessors and ivar names. anyway when running the Analyzer, and i know even the first time i started using cocos2d i get these messages when running analyze. here is a link to the screenshot. BTW how do you post pictures directly here?

http://www.flickr.com/photos/67382033@N02/6834352541/lightbox/

like the CCAtlasNode, CCMenuItem always had those analysis. I don't see any leaks in instruments though?

you think there is a fix for this? you think eventually when you get to publish the game to apple, that these would be a problem?

thanks again.

Posted 3 months ago #
Scryb
Member

I think that if you actually reuse the same scene many times like that, you might not need to release the scene at all, like Birkemose said. Just retain the scene as a property of that game manager you have, and then replaceScene with that scene and implement a full reset method. If you are not running low on memory while having both that scene and the menu scene(s) in memory, it will take less time and processor cycles to just switch back and not reload everything.

In both of my games I do that, since I don't have a bunch of different scenes and it's much faster to reset some variables, empty some arrays and reposition some sprites than to do the whole init process on the scene over and over.

Edit: And I'm pretty tired of seeing people tell others that scenes are released whenever you replace them – this ONLY happens if they are only retained by the director. If you retain them yourself they are not released of course.

Posted 3 months ago #
goodeats2009
Member

hi Scryb, so in your games do you do a push scene instead of a replace scene? do you have like a splash screen for a level completed or level failed on every start or end of your level? if so don't those count as a separate scene and do a replace scene so you can cycle through them throughout the game? and when you empty your arrays, do you do that before you exit the scene or before you restart the scene? do you just do [array removeallobjects]? i do have interest it that just so i don't have to reinitialized a lot of things. can you share some code or even a pseudo code will do. thanks

Posted 3 months ago #
Birkemose
Moderator
@goodeats2009
Simply create the scenes manually, an hold them in ivars. Retain it manually, that way it will not be released when you replace the scene. In stead of providing the factory method to replaceScene, you just provide the ivar.

Something like

Declare these in you app delegate header
```
CCScene* myMenuScene;
CCScene* myGameScene;
```
Then create these when you app initializes
```
myMenuScene = [ [ menuScene node ] retain ]; // retain the scenes manually, so that CCDirector not kils them
myGameScene = [ [ gameScene node ] retain ];
```
To start the myMenuScene
```
[ [ CCDirector sharedDirector ] replaceScene:myMenuScene ];
```
and later
```
[ [ CCDirector sharedDirector ] replaceScene:myGameScene ];
```
And when game is done ( it never is, but just so that you know ;)
```
[ myGameScene release ]; // good ractice to release in reverse order of creation
[ myMenuScene release ];
```
Now both scenes will stay in memory, and switching will be much faster. Of course it will take some resources, but on anything newer that a 3G, this is seldom a problem.
What is important to remember, is that [ myXxxxScene -init ] is only called once, and not every time the scene switches, so you have to handle more stuff in onEnter and onExit. That would be loading / saving level data, enabling / disabling touch, accelerometer, schedules, actions and whatever.
Posted 3 months ago #
goodeats2009
Member

Hi berkmose, so When I use retain that bumps up the reference count to 2? When u call release it decrements it to 1, so the Retain count is always 1 and never goes to 0 so the scene never gets destroyed right? So I would be moving most of the codes in the init method to onEnter and OnExit? I will try that tonight. Also can u give me advise on how to know which process is taking the most resources? In instruments I see all those mallocs, etc. Guessing malloc is memory allocation? I see memory address but I don't know how to trace it back to who's creating the allocs. Just so I can optimize it? Tnx

Posted 3 months ago #
Karl
Member
Don't worry about performance until your game feels sluggish on the lowest end device you plan to support.

What you want to do now is make sure your allocs/retains/releases are all matched in your init/dealloc methods, and that you have no circular retains going on (parent retaining child, which is retaining parent). If an object's retain count is at 2 (and no pending autorelease), that means it had better have 2 owners or else it's going to leak (Note: container classes such as NSDictionary and NSArray retain the objects they contain. If you're just going to keep an object in a container, don't retain the object yourself; let the container handle ownership). Make sure you're not double-retaining.

More generally, the simplest way to do things in cocos2d is:
- Build everything you need in the init method rather than onEnter. init gets called once and only once. onEnter gets called every time the scene is entered.
- Recreate scenes rather than re-using them.
- If you want to go to a temporary scene (pause screen or config screen), use pushScene/popScene since that preserves the previous scene.
- Otherwise use replaceScene to completely switch a scene.
- Make sure your data model class is managing its memory properly. Make all methods to it opaque (for example, make a "clear" method rather than accessing its internals like you were in your code above).
- Optimize only when things are slow, and only where directed by the profiler. Programmer intuition is usually wrong when it comes to identifying bottlenecks.
Posted 3 months ago #
goodeats2009
Member

thanks Karl, I agree and will try that tonight. a little confuse with:

"Recreate scenes rather than re-using them"

arent you re-using the scene by not letting it die?

thanks

Posted 3 months ago #
Birkemose
Moderator

@goodeats2209
The consensus approach on using scenes in cocos2d, is to completely create and destroy them each time you use them. I think that is what @Karl ment.
On the other hand, there is nothing wrong in keeping a scene in memory, and in the end, it imo is a matter of speed and style.

Still, what @Karl says is good advice, no matter if you keep the scene or not. You should at least get comfortable with how objects are retained and released, because it will save you an infinite amount of headache later.

Posted 3 months ago #
goodeats2009
Member

I totally agree, I appreciate you guys for the advice. I will try that tonight and let u know. Did you see the screenshot I posted though in analyzer? You know why I get all those warnings for ccatlas, Ccmenu? As far as I remember even when I was not using Ccmenu, those things were already showing up. Can I just ignore those or is there a fix? Tnx

Posted 3 months ago #
Karl
Member

Depending on how expensive it is to create your scenes, it can be better to re-use a scene rather than recreate it. The trade-off is added complexity since you must now manage both a "newly created" pathway and a "re-used" pathway for setting up a scene.

For a beginner, just sticking with the "recreate" approach is safer (less chance to introduce bugs). Once you're more experienced you can make a judgment call.

Posted 3 months ago #
Karl
Member

@goodeats2009 You can ignore warnings in the cocos2d code. I always compile cocos2d as a separate library so that I can turn on more stringent warnings in my own code.

Posted 3 months ago #
Birkemose
Moderator

I cant see anything from the screenshot. In my end ( not sure if it's me ) it is unreadable even in largest format.

I never ignore a warning, but with iOS5, xcode4, etc, there are more warnings and deprecated stuff in cocos, if your settings are not spot on. Especially if you are targeting iOS5.
My three rules of memory handling is
1) If you write retain somewhere, you must write release somewhere else. Inside a class, better write those one time to many, than one time to less.
2) If you add an object to a container, it is retained. As with retain, for each time you add an object to a container, you should remove it somewhere else.
3) Stay away from retained properties. If you need to expose a class pointer in a class, make it readonly.

Works for me.

Posted 3 months ago #
goodeats2009
Member

Sorry for the bad screenshot I'll take one again tonight and post it. Thanks both for the tip. Learning bit by bit now :)

Posted 3 months ago #
Karl
Member

Basically:

- Warnings in 3rd party library code are inevitable.

- Warnings in your own code are unforgivable.

Posted 3 months ago #
goodeats2009
Member

True :)

Posted 3 months ago #
goodeats2009
Member

hi guys, just want to post that analyzer again since the last one is unreadable. are these ok to ignore? thanks

http://www.flickr.com/photos/67382033@N02/6840101095/

Posted 3 months ago #
Karl
Member

Those are all in cocos2d. You can ignore them, or you could fix them and submit a merge request to riq ;-)

Posted 3 months ago #

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