I have a working iPhone app using SDK 4.0. It shows no leaks in the 'Instruments' tool, and I am fairly convinced that the code does not have any memory leaks.
I then tried to add iAds to the app, and it started showing memory leaks. In order to nail down the problem, I removed all additional code.
All that is left is an added AdBannerView to the .xib file (without doing a single modification to the working version of the code without iAds). This shows memory leaks.
Every time the view loads, the 'Instruments' tool shows 5 leaked blocks of 16 bytes each, with the Responsible Library 'Foundation', and Responsible frame
[NSCFString copywithZone:]
Further running the app gives me leaks from the Responsible library 'iAd' (2 leaks of 48 bytes each), and the responsible frame:
[AdBrandingFrame initWithFrame:]
Further, I also get 48 byte leaks with the responsible library 'UIKit' and responsible frame
-[UIView _createLayerWithFrame:]
Since there is absolutely no addition to my working non-leaking code, except an added AdBannerView to the .xib file, I wonder if it is Apple's code that causes the leak. Although the leak is relatively small, I would like to iron it out. I understand that there is a possibility that a leak shows up even though there may not be one (the pointers might still be held by the OS in some way that Leaks does not know about - It would be great to know if this is the case).
So I had two questions:
1) Is there any chance the problem is actually my code, and the leak for some reason only shows up after adding AdBannerView? If there is such a possibility, I would run another thorough code test.
2) If this is a problem with Apple's code and any of you have encountered this, are there any workarounds you have found?
Any help would be greatly appreciated. Thanks!
I just had the same issue. I think this has been fixed in IOS 4.1
When I test in 4.0 I got a couple leaks "NSCFString copyWithZone"
When testing in 4.1 all is good.
Related
I created a test project to confirm my memory leaks:
Project file: https://dl.dropbox.com/u/3703182/PickerView.zip
Basically a UIPickerView is connected to a datasource via IB. When it's connected to a datasource, it leaks. If not, no leak. I need to use a UIPickerView for an imminent app that needs to be released ASAP, unfortunately it guarantees a crash every 2 hours because of the leak. How can I use the UIPickerView despite the memory leaks without crashing?
EDIT:
It only leaks on device, not in simulator.
That is not a leak. It's an allocation.
If it was a leak it would show a red spike in the second row.
The real test for a leak is presenting and dismissing several times over. If you can do that and show that the allocations keep rising then there is a leak. Not otherwise.
Adding my comments as answer,
Your app will not crash due to this leak since it is a very small leak caused by framework which you dont have to worry about. The screenshot shows that it is in terms of a few bytes. If your app is crashing every 2 hours, that means there is something else which is using a lot of memory. Please check if you are using anything else in your code which could cause this and update the question with your finding.
In allocation tool, make sure you are checking the live bytes section and check how much it is going up. If it stays below 15-20 MB, you dont have to worry much anyways. Check this for more details about memory usage in app. Also check this XCode Instruments Allocations: Look at Live Bytes or Overall Bytes?.
This is the Apple library that is leaking. You cannot do anything about this. It is Apple's fault.
This isn't a leak you can control, it's internal... but this is a very small amount of memory and will not crash your application. I'd be interested in seeing what this looks like an hour in... Can you provide a backtrace of the crash? That would probably better help determine the real cause of the crash.
Any suggestions on how to work around this UITableView Leak?
Here's a link to a very basic test project that produces the problem:
http://www.maani.us/temp/Test.zip
To reproduce the leak:
Run the project with the "Leaks" performance tool.
In the table view, click '4' in the right-side Index to jump to section 4.
Scroll up a bit to display a couple of cells from section 3.
Wait for a few seconds. This generates a leak in the instrument.
I tested this both with version 4.2 and 4.3, both with the simulator and a device. All tests produce the leak.
Thank you for you help.
Are you testing this in the simulator or on the device? There are some known leaks with UITableViewControllers in the simulators that do not happen on hardware.
I ran this myself in my the simulator and the only leaks I am getting are for NSIndexPAth and generic 16 byte blocks, both of which are discussed on the internet as being leaked only on the simulator. You can also look at the leaks and see they are created and only accessed within the foundation framework. Therefore, it definitely seems to be a problem with the framework itself. One possible fix for this is to use a UIViewController and setup the UITableView yourself.
The test project above contains only the minimal code necessary to build a UITable and confirm that the leak is in the foundation framework (NSIndexPAth).
Yes, the leak happens on devices too.
The original code used a UIViewController that displayed a UITableView. That too produced a leak. I removed UIViewController to narrow down the problem and confirm that the leak still happens without too.
The only thing that removed the problem is removing the UITable section Index (sectionIndexTitlesForTableView:tableView), which is not a possible option in the final App.
Above given images is of my application leaks.
Here I want to understand that, in Extended Detail - you can see different colors like light green, light pink, light brown, light purple.
What does each color indicates?
Now the other confusion is "How to locate the code which is creating a memory leak?"
Upto what limit of memory leak - the actual iPhone can go on with.
(suppose 10 bytes no problem, 20 bytes no problem & 200 bytes a problem)
What does each color indicates?
Which color indicates our code / From which detail we can get to the code where we have allocated the object & forgot to dealloc it?
(For example - On clicking of UIKit second cell in detail - we cant get to the code)
Why we must resolve all the leaks? - even a single leak can chock up iPhone ?
Why iPhone allows leaks to be remain in memory? / why garbage collection isn't done automatically after termination of application?
If I try to dealloc objects which should be deallocated according to instruments, My application terminates abnormally. If I don't dealloc, My application runs perfectly, How?
Why it is suggested that you wait in a view up to 10 or more seconds, if there is a leak, leak will be detected by Instruments?
Ignore the colors, in that one the [DashBoard viewDidLoad] is the source of the leak, something in how it's initializing a URLConnection (possibly you did not free that when the connection was finished?)
Now to answer the other questions you had:
Why we must resolve all the leaks? -
even a single leak can chock up
iPhone ?
Yes. Part of the reason is not only that you will simply run out of memory, but since there is only so much memory to go around for the whole phone a watchdog application is constantly monitoring your app and will shut it down early if it sees memory use only ever growing...
Why iPhone allows leaks to be remain
in memory? / why garbage collection
isn't done automatically after
termination of application?
All your application memory is freed when the app quits.
If I try to dealloc objects which
should be deallocated according to
instruments, My application
terminates abnormally. If I don't
dealloc, My application runs
perfectly, How?
Here I can't help, you really need to read more on the retain/release memory cycle... if you release an object that has a retain count of 0, the app crashes because the object is gone.
Why it is suggested that you wait in
a view up to 10 or more seconds, if
there is a leak, leak will be
detected by Instruments?
Because instruments works by sampling memory every so often, so it might take a little bit for instruments to get around to reading the memory after an action.
First of all, the things in the stack are colored by which library they come from, so it doesn't contain that much information.
Second, instead of worrying about how much leakage the iPhone can take, I'd focus on not having it leak.
To find leaks, there are a couple options:
Use the CLANG static analyzer when building your project
Look for leaks manually. You must always follow The Rules of memory management: if you alloc, retain, or copy an object (including using #property (retain) or (copy)), you must release or autorelease it.
The colors represent the different libraries the call stack is going through.
The leak is caused by the frame in your code that made the allocation, even if the actual allocation is taking place deep within an OS library. Instruments is showing you exactly where the leaked memory was allocated. You'll have to figure out which line in your code resulted in the leaked allocation, which will be one of the frames in the stack on the right.
The actual iPhone doesn't have much RAM available to your application. I tend to conservatively estimate about 25MB of RAM for my application to work with. Any leak, no matter how small, can sink the proverbial ship if the code is used enough.
Look for your application name in the stack extended view. Memory allocation usually shown in the end, so you know exactly which library is responsible for memory allocation. So you should trace from the line your code appear downwards till the end. Colors just make easier to trace lines of code, that are related to same libraries. Same library calls will be colored with the same color.
As for tracing leak itself. First go to your application call by double-click on the line in extended view and try to understand what exactly leaks. Sometimes you can replace the leaking call with non-leaking substitute. For example, I used a call imageNamed to retrieve images from the bundle, the application was constantly crashing because of memory shortage. I just googled imageNamed leaks and found very useful article on how to implement image cash in my application. Indeed, imageNamed API leaks. There are API that leaks in iphone SDK.
Also, try to check how you're working with alloc/retain/release and so on, whether you release or autorelease your allocated memory.
Good luck in your detective work.
I too have problems with leaks in instruments. I run my app today for the first time using leaks and found several leaks. Leaks that shouldn't be leaks because there is no way for them to leak, unless some magical code is executing and raising the retain count of my objects. I understand the memory management guidelines, know how to use autorelease pools, etc. But even an empty view based app contained leaks if i put a few controls on it. And just click around 2-3 times. Go ahead and try it. I don't really understant the information instruments is trying to provide. Are those "leaks" really leaks, or just things that are suspicious to the instruments app? Should an empty app with no user code, only a few controls put on an empty view leak memory?
i'm only create an project with a Utility Application template.
This template has a native memory leak when i push "info button" to
flip the view.
Anyone know how can i fix this leak ???
I just make an new project from this template,
i don't add new objects.
That might be a leak or it might not be a leak. If you were to add the backtrace of the allocation, that would be helpful.
More likely than not, it isn't a leak, but some bookkeeping information that is being stashed away by dyld that leaks/Instruments loses track of.
Given that it is 128 bytes and I'm guessing there is only one of them, I would encourage you to file a bug via http://bugreport.apple.com and then forget about it for now as, in the unlikely case that it really is a leak, you will be equally as unlikely to be able to fix it from within your application.
Hope this helps.
From: http://www.cocos2d-iphone.org/forum/topic/2460
"The simulator has bugs related to singletons and llvm stuff that are incorrectly reported by Instruments. Always check your leaks on the device itself."
Got the leak doing this:
XCode 3.2--
File, New Project, Navigation-based Application
Give it a name
Build It
Run With Performance Tools -> Leaks
When Instruments comes up, click on Leaks (you might have to click the little icon at the bottom that looks like four boxes within a box)
About 7 seconds after running you should see the leak:
-- Malloc 128 Bytes, some Address, 128 Bytes, CoreGraphics, open_handle_to_dylib_path
I traced it to this code in the AppDelegate:
//APPLE CODE
- (void)applicationDidFinishLaunching:(UIApplication *)application {
// Override point for customization after app launch
[window addSubview:[navigationController view]];
[window makeKeyAndVisible];
}
I broke out the navigationController (did a separate alloc and release) and COMMENTED OUT the addSubview: action - there was no leak - and, obviously, the screen was blank.
It wasn't until I attempted addSubview that the leak occurred. Since there are numerous ways to add a subview, I tried those. Each resulted in the leak or a blank screen.
I tried it on a real ipod touch. No leak was reported.
Probably just a simulator thing ...
Leaks has flagged open_handle_to_dylib_path in CoreGraphics for me as well; there is definitely something flagged here. Since it is merely 256 bytes at its heaviest, I fired off a bug report to Apple and called it done. You can then set a rule in Leaks' configuration to ignore the report.
As bbum pointed out, there might be serious voodoo at work. I seriously doubt Apple would let leaky frameworks go through QA -- especially since it's so easy to reproduce.
This must be a bug. It appears in Apple's own example, PageControl, found here:
http://developer.apple.com/iphone/library/samplecode/PageControl/index.html#//apple_ref/doc/uid/DTS40007795
In the current SDK utility template is no leak. How did you get the impression there's a leak in the template? It's just allocating memory which is needed for the views.
A leak is memory to which no pointers exist and which cannot be freed any more.
I had the same problem, but was able to understand why it happened. And I have given a brief info regarding this problem in this article
Might be useful for you.
I am trying to locate leaks using instruments, but the leaks I see there are like the ones in the next picture:
leaks
As you can see there's no information of which line of code is exactly leaking. All leaks I have, around 20, are like this, or in other words, the leaks don't show any line of my code in particular.
The leak in this picture is related to "_CFAllocatorSystem" (???) on the CoreFoundation and I have others that simply say GSEvent. I have no clue of what's generating these.
How can I discover that?
thanks for any help.
I think you want to go into instruments after running under leak and select "Source View". Then you need to drag your source files into the instrument window. It will then show the lines in the code where the leak occurs along with the call stack.
Some toss off code of mine leaks a view. It looks like this in Instruments:
alt text http://img688.imageshack.us/img688/9669/screenshot20091028at131.png
The thing that Leaks shows you is, the trace to the code that allocated the object that is leaking (which means it is retained but your application has no variables left that have that address). What it does not show you is just where the object should have been released to not cause the leak, for that is impossible to know (it is possible to find where release is currently being called, but that may not be so helpful).
So what this trace is telling me, is that some bit of memory allocated by the system is being retained by you, and then the reference forgotten - one key is the "PurpleEvent" line, which is common in a thread dealing with timer events or perhaps notifications. It could be you received a notification and kept something from it, without releasing it later on.
If you know about at what point the leak occurs, you should be able to isolate what code is running during that time.
See here and especially this quote:
This list informs you about the leaked objects' types, sizes, addresses, and even their call stacks.
Then you can trace the source of leaked memories through the call stacks.
The stack trace shows you exactly which line is the culprit. Apparently line 14 in main.m in your case. Dont know what you confused about?
The guilty was the accelerometer and I am compiling for OS 3.0.
In other words, the accelerometer that Apple said its leaks were fixed, is still leaking like hell.