I am using a sqlite query to get nutrient values for a specific food item from USDA database.
The query works fine, when tried in simulator, but results in crash on device sometimes.
I am including the USDA database in the app itself. Also the table on which the query is getting executed holds more than 5 lac records. I am getting 'Level 1 Memory Warning' at the launch of application. I cannot go for webservices, as the requirement is to give offline support.
Any suggestions how to handle this situation??
Edit :
In the log I get Signal 0 message
Program received signal: “0”.
Data Formatters temporarily unavailable, will re-try after a 'continue'. (Unknown error loading shared library "/Developer/usr/lib/libXcodeDebuggerSupport.dylib")
You are exhausting your app's memory. I am not a DB expert but you will have to use some special techniques to access your huge data base. Perhaps execute multiple queries serially in different sections of the DB. Or divide the DB into segments. Following are some references related to the crash you are seeing-
Program received signal: “0”. Data Formatters temporarily unavailable
Data Formatters temporarily unavailable
Data Formatters temporarily unavailable, will re-try after a 'continue'
There are more if you search for the error message.
I guess the size of the database is causing the crash...
If you are using this database as read only then you can use the compressed and encrypted form ... you can get more details from here http://www.hwaci.com/sw/sqlite/cerod.html
this might help you get rid of the memory warnings..
here is another link which can help you reduce the size of the database....
How to reduce the size of an sqlite3 database for iphone?
Memory Related Crashes are quite common for ios apps I've noticed that more stable apps tend to manually manage memory alot over just letting the device manage it. I think if you split it up into sections instead of reading off one file and like akshay said index the tables it will be more stable. You could try reading files from compressed zips which would be more efficient over just plain old reading.
Related
I have followed Cocoa is my girl friend's tutorial here, which is based on a subclass of NSOperation to fetch and load big number of records in a background thread, but in my case I have several thousands of records which take 1-2 minutes of continuous loading from a remote web service. The app have web service proxy classes generated using SudzC. There is no memory leaks detected. The problem occurs after the app finishes loading and saving this huge number of records into sqlite database (using core data), I notice that this import/save operation consumes so much memory, i.e. after this operation finishes, I use the app features for couple minutes (opening table views, writing text, etc ...), then i will see a crash that happens due to low memory, if I didn't include the import/save operation the app works fine without any low memory crash!
does anybody have a clue for this problem ?
thanks in advance.
i am getting a serious issue
Program received signal: “EXC_BAD_ACCESS”.
Data Formatters temporarily unavailable, will re-try after a 'continue'. (Unknown error loading shared library "/Developer/usr/lib/libXcodeDebuggerSupport.dylib")
kill
quit
The Debugger has exited with status 0.(gdb)
Note:
Problem occurs when i am fetching approx more than 5000+ data on tableview (using Core data)
If data is not huge then application doesnt crash.
EXC_BAD_ACCESS means: Exception Bad Access.
This is not a Core Data error. It is an exception from trying to access an object that has been released.
Turn on NSZombie, set a breakpoint on objc_exception_throw. Then run your app again in the debugger and track down the over-release.
Don't know, but it appears to be happening because of the amount of data you are loading. This sounds like a lot of data to be loading on an iPhone. Is there anyway you can reduce the volume? Perhaps you could create a table that contains summaries of your data. Or perhaps page load 20 or 30 records at a time rather than the full 5000.
This is a rather general question, as I don't have any solid evidence atm.
I have an iPhone app with about 20,000 users. It allows users to message each other, and saves those messages in core data. The only other thing it saves in core data is the users profile, a copy locally and a copy on the server.
I have a small percentage of users complaining that they receive messages but nothing shows, when they send a message (which immediately goes into core data then shows on screen) it disappears immediately. Nothing but a full restore seems to fix it, and from what I can gather, even a restore which involves them restoring a backup they just made doesn't fix it.
My first thought was that core data must have become corrupted in some way ... but the messages they attempt to send actually do send, and this would be impossible if their local profile had become corrupted too.
I've never been able to recreate it, or found anyone face to face who has had a similar problem.
Does anyone have any suggestions on what could occur in core data that could lead to a situation like this so I can start to try and track down the problem? I'd estimate it's happening with about 1% of users.
Once again, sorry for the generality of the question, but it's all I have to work with just now!
Thanks
** Edit
Just to clarify, deleting the app and reinstalling it, does not fix the problem when this happens.
** Edit
I just had some more information from a user who is suffering from the problem ... the information my app saved in core data still exists after the app has been deleted and re-installed, all of it. I have deleted and re-installed my app hundreds of times over the last year, on countless different devices, and every time I delete and re-install, all previous data stored in core data is completely erased .. yet for these users, this is not happening. Does this sound like an iPhone issue that basically requires a restore?
** Edit 03/12/2010
AT LAST! I have some real solid information to work on. I added flurry to my latest release so I could track any core data error messages, and was able to correlate the errors received with a user id that I knew for a fact was experiencing the problem ...
The error is: "Msg: Error Domain=NSCocoaErrorDomain Code=133020 'The operation couldn’t be completed. (Cocoa error 133020.)' UserInfo=0x39c7c0 {conflictList=( 'NSMergeConflict (0x39c700) for NSManagedObject (0x38ad00) with objectID '0x375c30
Unfortunately, the error is trimmed. Flurry must have limit on the size of the message it can pass.
I don't have access to my mac and code just now, I'll start investigating as soon as I do and post back with some source code and any findings I have.
I'm having a problem like that right now. So far I have figured out that the same object is modified in two NSManagedObjectContext-s. The object X has (at least) two persistent attribites, a and b, one thread changes a, another thread changes b, and CoreData cannot merge.
The key phrase in the error message is NSMergeConflict:
Error Domain=NSCocoaErrorDomain Code=133020 "The operation couldn’t be completed. (Cocoa error 133020.)" UserInfo=0x1544c7d0 {conflictList=(
"NSMergeConflict (0xc489f40) for NSManagedObject (0xd833ca0) with objectID '0xd82b7c...
Not sure this really helps, but at least it tells you what might go wrong...
Does anyone have any suggestions on what could occur in core data that could lead to a situation like this so I can start to try and track down the problem?
About a zillion different things.
Your real problem is that you are trying to debug in a speculative fashion. To properly fix this bug, you first need to know how to reproduce the bug. There's no other way to know if you've fixed it after you've tried something.
I would not start by blaming the underlying frameworks like Core Data. Odds are your program is the one losing the data. Start with that assumption.
Does it affect these users from the moment they set up there account? Could it be something to do with their username/id/personal information?
If deleting the app completely and reinstalling doesn't solve the problem, then I'm at a loss for how it could be core data - as you yourself say, I often do this and it removes all core data each time. So if it is core data corruption, it would have to be in your construction of the core data instead of the database itself. I don't think it likely that only people who install your app would have problems with core-data being retained.
If you have contact with a user experiencing this problem, I would get them to try to create a new username that is "safe and normal".
Good Luck.
I've got an app that caches a pretty decent amount of data in memory after parsing a csv file, and also displays an MKMapView. After scrolling across the country from one end to the other in the MKMapView, the app inevitably gives me one or more:
Received memory warning. Level=1
Received memory warning. Level=2
and finally crashes due to low memory. I've been trying to figure out a means of managing either the memory of MKMapView or my own data (which comes from a csv file - the csv file needs to be written to frequently, so I'd like to keep it in memory in some fashion or other if possible, unless there is a better means of handling the issue.
Any ideas?
Use instruments to determine how much memory the cached CSV is taking vs the MKMapView. If the CSV is the problem, then look at storing it using CoreData or sqlite.
I have a simple Core Data application, with a table view and a drill down view. When I build and run in the simulator, all of the data in my database loads and the table view/drill down views function properly.
When I build and deploy to a device, my application only loads a small subset of the data (a few sections, A - C). I have no warnings nor build errors. Has anyone run into this problem? Any suggestions?
While I have not run into that issue, I would debug this using log statements. Put in logs through your loop, at the end of the NSURLConnection (assuming you are getting the data from the net) and see what is coming down, etc.
There is no reason for the default to be limiting the data and contrary to some other advice, you have at least 20mb of RAM to use even on the first device. Plenty of room to load a ton of data. Spit out the data stream to the console from the phone and see what you are getting. That is where I would look first.
I think what #theband might be talking about is the fetchLimit property of NSFetchRequest (and it's corresponding property fetchOffset). With these you can have more control over the fetching, and if you have a considerable amount of data, you will need to do that since you can't really plan on having more than about 8MB of RAM for your app on most devices.
The problem is with the device as sometimes it does not load the entire data. The solution would be checking on the limitation of data.