我正在做 2 个核心数据提取,当它们大约同时执行时,它们会导致主线程死锁,从而导致我的应用程序冻结。
提取是在主线程上进行的。处理它的一种方法是确保不会在同一时间进行提取,但我无法控制何时进行提取。有没有其他方法可以避免这种僵局?
暂停应用程序时的堆栈跟踪是:
#0 0x9a5d191a in __psynch_mutexwait ()
#1 0x9166713b in pthread_mutex_lock ()
#2 0x01e5d591 in -[_PFLock lock] ()
#3 0x01e5d56a in -[NSPersistentStoreCoordinator lock] ()
#4 0x01e720ee in -[NSPersistentStoreCoordinator executeRequest:withContext:error:] ()
#5 0x01e70539 in -[NSManagedObjectContext executeFetchRequest:error:] ()
#6 0x0007cd62 in -[CoreDataHelper fetchEntity:predicate:andSortDescriptors:inManagedObjectContext:] at /xxx/CoreDataHelper.m:150
#7 0x000075f6 in -[RemindersListViewController refreshReminders] at /xxx/RemindersListViewController.m:64
#8 0x000082f8 in -[RemindersListViewController refreshGUI] at /xxx/RemindersListViewController.m:187
#9 0x00003735 in __58-[AppDelegate setTabCountAndScheduleRemindersInBackground]_block_invoke_2 at /xxx/AppDelegate.m:114
#10 0x022dc53f in _dispatch_call_block_and_release ()
#11 0x022ee014 in _dispatch_client_callout ()
#12 0x022de7d5 in _dispatch_main_queue_callback_4CF ()
#13 0x0261aaf5 in __CFRunLoopRun ()
#14 0x02619f44 in CFRunLoopRunSpecific ()
#15 0x02619e1b in CFRunLoopRunInMode ()
#16 0x02fd77e3 in GSEventRunModal ()
#17 0x02fd7668 in GSEventRun ()
#18 0x00d9dffc in UIApplicationMain ()
#19 0x0000297d in main at /xxx/main.m:16
编辑:访问核心数据的不同部分正在尝试执行获取请求。他们都在调用这个方法:
NSArray *reminders = [[CoreDataHelper sharedInstance] fetchEntity:APReminderEntity predicate:nil andSortDescriptors:[NSArray arrayWithObject:dateAscendingDescriptor] inManagedObjectContext:nil];
CoreDataHelper.m
- (NSArray *)fetchEntity:(NSString *)entity predicate:(NSPredicate *)predicate andSortDescriptors:(NSArray *)sortDescriptors inManagedObjectContext:(NSManagedObjectContext *)context {
DLogName()
if (context == nil) {
// Use default MOC
context = self.managedObjectContext;
}
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:entity inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDescription];
if (predicate != nil) {
[request setPredicate:predicate];
}
if (sortDescriptors != nil) {
[request setSortDescriptors:sortDescriptors];
}
NSError *error = nil;
NSArray *entities = [context executeFetchRequest:request error:&error];
if (entities == nil) {
DLog(@"There was an error fetching entity: %@ Error: %@", entity, [error userInfo]);
entities = [NSArray array];
}
return entities;
}
编辑 2:我只是尝试将我的 fetch 请求放在一个@synchronized
块中(如本文中所建议的那样),到目前为止它似乎工作得很好......我正在正确的线程上访问我的 MOC.. MOC 被初始化为_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];