CODEWITHSUNDEEP
iosmultithreadingcore-dataconcurrencyfreeze
Douglas Ferreira
Douglas Ferreira

Reputation: 2279

Core Data freezing all the app

I'm having problems with Core Data concurrency on my iOS app. On my executeFetchRequest I tried to synchronize the managedObjectContext request, but some times this method makes my app freeze.

- (NSArray *)synchronizedWithFetchRequest:(NSFetchRequest *)request andError:(NSError **)error
{
    @synchronized(self.managedObjectContext)
    {
        return [self.managedObjectContext executeFetchRequest:request error:error];
    }
}

I've already tried many things like lock/unlock, performBlock/performBlockAndWait, dispatch_sync/dispatch_async and nothing seems to work.

Managed Object Context creation:

 ...
    _managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
    [_managedObjectContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];

Is there some way around this? and keep my request returning the results objects on this method?

Thanks!

Upvotes: 1

Views: 1149

Answers (1)

Dan Shelly
Dan Shelly

Reputation: 6011

Synchronising on the MOC suggests that there is more than one thread accessing the same MOC.
That in itself is a violation of CoreData concurrency protocols.

This access is prohibited unless it is wrapped in the context performBlock: method (or its "wait" counterpart). this will negate the need for the @synchronized block altogether.

This thread/queue "boundness" extends to the contexts fetched/registered managed objects, and so, you will not be able to access them as the return values of your method.

Upvotes: 2

Related Questions