提取时Coredata崩溃 [英] Coredata crash while fetching
问题描述
我在生产应用程序中遇到一些奇怪的coredata错误，并且我能够掌握崩溃报告。
I am getting some weird coredata error in the production app and I was able to get hold of the Crash Report.
有时会崩溃并显示以下消息
Its Crashing with the following message at times
***对象0x17e400000的错误：释放未分配的指针
*** error for object 0x17e400000: Freeing unallocated pointer
***对象0x17fd03730的错误：未分配指针重新分配
*** error for object 0x17fd03730: pointer being reallocated was not allocated
这是堆栈跟踪
Crashed: SQLQueue 0x13ff15250 for datastore.sqlite
SIGABRT ABORT 0x0000000183986014
0 libsystem_kernel.dylib __pthread_kill + 8
1 libsystem_pthread.dylib pthread_kill + 112
2 libsystem_c.dylib abort + 140
3 libsystem_malloc.dylib _nano_vet_and_size_of_live + 330
4 libsystem_malloc.dylib nano_free + 220
5 libsqlite3.dylib sqlite3_finalize + 244
6 CoreData -[NSSQLiteConnection _finalizeStatement] + 100
7 CoreData -[NSSQLiteConnection releaseSQLStatement] + 52
8 CoreData newFetchedRowsForFetchPlan_MT + 2420
9 CoreData _executeFetchRequest + 72
10 CoreData -[NSSQLFetchRequestContext executeRequestUsingConnection:] + 60
11 CoreData __52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke + 260
12 libdispatch.dylib _dispatch_client_callout + 16
13 libdispatch.dylib _dispatch_barrier_sync_f_invoke + 84
14 CoreData -[NSSQLDefaultConnectionManager handleStoreRequest:] + 208
15 CoreData -[NSSQLCoreDispatchManager routeStoreRequest:] + 288
16 CoreData -[NSSQLCore dispatchRequest:withRetries:] + 200
17 CoreData -[NSSQLCore processFetchRequest:inContext:] + 108
18 CoreData -[NSSQLCore executeRequest:withContext:error:] + 504
19 CoreData __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke + 4512
20 CoreData -[NSPersistentStoreCoordinator _routeHeavyweightBlock:] + 276
21 CoreData -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 408
22 CoreData -[NSManagedObjectContext executeFetchRequest:error:] + 572
23 CoreData -[NSManagedObjectContext(_NestedContextSupport) _parentObjectsForFetchRequest:inContext:error:] + 456
24 CoreData __82-[NSManagedObjectContext(_NestedContextSupport) executeRequest:withContext:error:]_block_invoke + 584
25 CoreData internalBlockToNSManagedObjectContextPerform + 92
26 libdispatch.dylib _dispatch_client_callout + 16
27 libdispatch.dylib _dispatch_barrier_sync_f_invoke + 84
28 CoreData _perform + 232
29 CoreData -[NSManagedObjectContext(_NestedContextSupport) executeRequest:withContext:error:] + 188
30 CoreData -[NSManagedObjectContext executeFetchRequest:error:] + 572
31 *MY_APP* NSManagedObject+MagicalRecord.m line 50__67+[NSManagedObject(MagicalRecord) MR_executeFetchRequest:inContext:]_block_invoke
它确实发生在主线程上，我对如何调试它感到困惑。虽然看起来像一个内存问题。同样，在使用工具时，遇到 NSPrivateQueueConcurrencyType 时，它会在应用程序中显示一些泄漏。
It did happen on the main thread and I am puzzled on how to debug this. Looks like a memory issue though. Also while using instruments its showing some leaks in the app when it comes across NSPrivateQueueConcurrencyType .
应用正在广泛使用MagicalRecord，这是导致上述崩溃的应用中的代码块。它只是从主线程正常获取。最有趣的是，它随机崩溃，即它并不总是崩溃，但有时在获取时崩溃。
App is using MagicalRecord Extensively and here is the code block in the App Which leads to above crash. Its just a normal fetch from Main Thread. Most interestingly it crash randomly, ie it doesn't always crash but at times it crashes while doing a Fetch.
NSPredicate *filterPredicate = [NSPredicate predicateWithFormat:@"code == %@ and pid == %@", aCode,pid];
Permission *aPermission = [Permission MR_findFirstWithPredicate:filterPredicate];
推荐答案
访问（写或 Read ）在除 Managed Object Context Queue 之外的任何线程上的Managed Object导致未定义的行为&会导致随机的奇怪的崩溃。
看来您的托管对象上下文是使用创建的NSPrivateQueueConcurrencyType &您在主队列上执行的获取。这是奇怪崩溃的根源。
您可以使用 NSMainQueueConcurrencyType初始化或将所有 MOC fetchRequests 嵌套在 [MOC performBlock：{...}]
Accessing (Write or Read) a Managed Object on any thread other than the Managed Object Context Queue causes undefined behaviour & leads to random weird crashes.
It looks like your Managed Object Context was created with NSPrivateQueueConcurrencyType & your performing fetch on the Main Queue. This is the source of the weird crash.
You can either initialize MOC with NSMainQueueConcurrencyType or nest all your fetchRequests inside [MOC performBlock:{...}]
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