I am getting a lot of strange EXC_BAD_ACCESS crashes on the iPad that only happen on the device and not in the simulator. I am assuming that they are somehow memory related, but I am not sure. They all happen with image context related functions.
One strange example is using CGImageCreateWithImageInRect. For example, if i run through a bunch of UIImages and crop them with CGImageCreateWithImageInRect, it will always crash at specific arbitrary sizes. Like, if I crop them all to 200x200, it crashes out after processing 12 images. If i crop them to 210x210, it works no problem.
The EXC_BAD_ACCESS happens inside of "memmove" called from "CGBlt_copyBytes". That is all the debugger shows me strangely enough. I can't see the callstack going up to any of my methods.
All of this works fine in the simulator!
I know this is all very vague, but if anyone has any ideas, they would be greatly appreciated.
Start by doing things like checking for zombies, and running clang (Build & Analyze) to see if you have memory management issues. I think you'll need to post more code, because this does sound like memory stomping.
Related
I am working on an iPhone game which receives memory warning that I am not experienced enough to interpret. I have been watching some iTunesU tutorial but I am still not very good at this..
I have received various memory leaks whilst running my game and I wanted to understand how to interpret the stack trace show in Instruments properly.
I attach a screenshot of the ObjectAllocation instrument output . Even when I zoom filter I don't manage to filter the data in the ObjectSummary .
The peaks in memory usage in 1 happen when the GameScene is initialized and all the data is loaded (ParallaxBackground, CCSpriteBatchNode) and Sprites and bullets frames are created (in an CCArray of spriteFrames).
The big blue peak is just at load time but the app freezes and then crashes only after a while and from the graph I see that the memory usage (blue bar) has gone down.. so I don't quiet get that. Also, whenver I try to use the leaks instrument the App crashes..
I know is a very silly question for someone experienced, but I just need some extra help getting started with this toolset.
I think the memory problem are due to the sprites I allocate in sprite cache classes, but I am not sure on this and hence wanted to investigate this using Instruments but can't find out how to see what is the object causing the memory warning and how to access the stack trace..
PS: I am running on an iPod 4th generatio and I am using Cocos2D as library
EDIT: I do not also understand why if the Live Bytes are only 1.01 MB the App crashes and why I still receive a memory warning (see black flags). Is it due to some pointer referencing to some null variable or due to an excessive memory allocation? 1.01 MB doesn't seem much to me..
EDIT 2: Following Marion's advice I used the Activity Monitor and realized that the effective real memory usage is 55.39 MB. I misinterpreted the "live bytes" word. I will try to dig into this further and will leave the question as unaccepted for now to allow other people contribute. If I won't have any other answer within one-two days I'll mark as accepted the current answer. Thanks!
Thanks a lot!
If you want to find leaks, use Leaks instrument instead of Allocations. To find out, how much memory use at the moment, use ActivityMonitor.
If you will have problems with memory in cocos2d, you can try to purge cache. In cocos2d you can purge CCTextureCache, CCSpriteFrameCache, CCAnimationCache. It will release unused textures and frames.
If you want to check if all of unnessesary textures were removed from memory, you can place breakpoint to CCTextureCache class and call, for example, sharedTextureCache and look throw the content of textures_ dictionary. Or add some method to this class to be able to dump current state of cache.
I have an app that can import images. My app doesn't need large images, so if I see an image larger than 512 pixels on a side, I resize it.
I'm using some image resizing functions that I borrowed from:
http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way
The resizing functions work really well most of the time, but I have some large photos in my library that are 5616x3744. When I try to resize this image, it sometimes causes a crash while executing CGContextDrawImage() (about half the time it crashes, although once I was able to process about 20 images before it crashed). It is not consistent about which images it crashes on yet.
I haven't tried this in the simulator yet, but have been running on my iPad in develop mode while connected to the debugger. When the app crashes, it exits right out of the debugger and returns with signal "0".
I was wondering if there might be a memory issue, but when I run it with the allocations instrument, it doesn't go past about 44meg before crashing, and my app gets no memory warnings.
Is the resize operation just allocating a HUGE amount of memory that causes an out of memory crash without getting any kind of warning first?
I guess I could restrict my app to smaller images, but I would like to know why the crash is happening to make sure that it isn't something random that could bite me later.
Any help is greatly appreciated!
Thanks,
Ron
I've done a bit more debugging and I think what is happening is that the OS is killing my App for allocating too much memory. Since it is done in a single operation, the OS doesn't get a chance to notify my app about running out of memory, and just kills the app. Kind of sad that an iPad can't even resize a single 20 megapixel photo without being killed. Hopefully the iPad 3 will have at least 1gig of memory! My iPhone4 will do 70 megapixel photos without a problem.
This just started happening when I tested on my iPad using the new 4.2.1 firmware using the iOS 4.2 final SDK, however I've changed a lot of code since the last time I tested on my device so I can't be 100% sure it's 4.2.1 related though it seems very likely. I was previously testing on 4.2 beta3 with 4.2 beta3 SDK with no problems.
I have a view that does some Quartz 2D drawing. Every time I call [self setNeedsDisplay] on it to update the drawing, the application crashes with a Signal 0. I've never had a problem with this before and was always using that call to redraw the view without issue.
Has anyone run into this before or has any info on what the cause could be? The crash is happening before drawRect: is called, so I'm not sure how to debug this.
It does not crash in the simulator, only on the actual device.
No crash logs are generated on the device and the exact error that is displayed in the debugger is this:
Program received signal: “0”.
Data Formatters temporarily unavailable, will re-try after a 'continue'. (Unknown error loading shared library "/Developer/usr/lib/libXcodeDebuggerSupport.dylib")
Also, before anyone suggests that it's an issue with using too much memory as signal 0 errors often are, the app is using only 1.4mb of ram when the crash happens (viewed in Instruments) and I don't see a big spike of allocations or anything before it crashes. It crashes with just over 1.4mb used.
Update: I've been working on this more, here's what I've found so far.
There seem to be some issue with the 4.2 final SDK and iOS 4.2.1 but they don't seem related to this particular issue.
I've downgraded to 4.2 beta 3 that was previously working for me, and it is still crashing the same way
If I don't override the drawRect: method in my class and I call setNeedsDisplay is DOESN'T crash.
If I override drawRect: even if I keep it empy (just calling [super drawRect:] or even leaving it completely empty) it DOES crash.
So for some reason, just implementing drawRect: at all is causing this problem. It makes no sense though as I've implemented this code this same way since I started this project and am only now experiencing this issue.
Update: It turned out to be a memory issue after all related to the size of the view that I'm doing the drawing in. Although the Instruments tool seems to not be displaying it for some reason, according to this post: iPhone + UIView. Enormous memory consumption during drawRect. Any strategies for reducing this? when using setNeedsDisplay: on a large view there is a huge memory spike and the only real way to fix it is to use smaller tiled views and draw in each separately.
I removed a bunch of images from my scrollview and was able to see the memory warnings without the crash. I found if I lower the size of my drawing view in the scroll view, I no longer get memory errors. I had the drawing view at almost 4000x4000 before. Lowered it to 3000x2000 and no more crashes.
Now the issue for me is I need one contiguous drawing view, due do the nature of what I'm drawing I'm not sure it's possible to tile it. But that's a question for another post.
Try this Other Answer/Solution
Basically it is likely a memory problem.
What does the error warning: check_safe_call: could not restore current frame usually indicate? I've read in other places that it's a memory issue. Is it always a memory problem?
I'm getting this error on the device (not the simulator). NSZombieEnabled shows nothing. If I Build and Debug, my debugger window shows nothing. The peak memory isn't that high (3MB). It just crashes with the same error every time after scrolling around a map.
Any ideas how to debug this? Thanks.
Edit: I added the reason for my crash in an answer below (creating too many SQLite connections). If anyone else gets this error and finds their solution, please post it below. It seems like an error message with multiple causes.
I've seen this a few times, but never been able to actually pinpoint it to a problem outright. Although, the times I've seen it usually there has been some kind of infinite loop or recursion gone wrong and the debugger will catch it. I don't know if you've left it long enough, but after a while, the debugger should start to load the stack frames it does have and display them in the debugger window. There you should be able to see what is going wrong.
Like I said, usually when I've seen this its been due to infinite loops or recursion and the debugger will show upwards of 5000 calls to the same function, so finding the problem shouldn't be too difficult - but, saying that, it may not be the exact issue.
Just my two cents.
This warning also may happens when to use stack based block out of the scope the block defined without copying it.
http://developer.apple.com/library/mac/documentation/cocoa/Conceptual/Blocks/Articles/bxUsing.html#//apple_ref/doc/uid/TP40007502-CH5-SW2
http://www.friday.com/bbum/2009/08/29/blocks-tips-tricks/
I came accross this problem too but I found that it was caused by an image that was at too high a resolution. It would work perfectly in the simulator but not on the device. I resized the image to 320x480 pixels at 180 pixels per inch and now it works perfectly.
Hope that helps
I found the error in my code. It turns out that the SQLite database I was using was causing the crash. I was forgetting to close my database connection, and each time the code hit a particular function, I'd open a new connection. Eventually there were too many, and the app crashed.
It's looking like a lot of these errors are to do with a kind of overload (as Jasarien says).
I've developed my application using my 3G device to test with. Upon giving this to a friend to test, he's noticed that it crashes..I've had a look at the crash log, but it's not much use except for the "EXC_BAD_ACCESS" statement after a few memory warnings.
On my device, I can use the imagePicker lots, and each time a photo is taken I get a memory warning, but this doesn't cause any problems.
On my friend's device (also a 3G), after a couple of images chosen from the camera, the app crashes.
So, my question is.. I think something is being deallocated because of the memory warning - but only on my friend's device, and then after deallocation, it's trying to be used again. How can I find out what object is being called? I can't use NSZombies because this is a remote (beta) device.
Help please!
Also if anyone has any ideas why my device can pick image after image without any problem and his can't...that would be most helpful
Thanks!
EDIT: New discovery.. I'm getting this error message too: KERN_PROTECTION_FAILURE which I understand to be something to do with data access. The crash seems to happen right after I save the image got from the UIImagePicker. Any ideas?
You may be over-releasing something. If you're running Snow Leopard, run the Static Analyzer (Cmd-Shift-A) and look for memory errors.
The fact that it crashes after a memory error suggests that a UIViewController has released its view. Do you have any UIViewControllers that observe NSNotifications, or otherwise might change their IBOutlets while they are off-screen? This is a common cause of this kind of crash. Make sure you're correctly memory managing your IBOutlets. UIViewControllers should never mess with their IBOutlets (or their UI components at all) when they are off screen. Even if you don't make this mistake, if you're not implementing things as noted in the above link, you can still crash after memory warnings.
MemoryWarning was a pretty good idea, and things have improved, but Apple still hasn't quite cooked all the issues around how it plays with UIViewController. The developer still needs to be very careful.
You should have your friend come to your computer and run it with NSZombieEnabled. That's the best way to debug these issues.