For thread-safety's sake why don't you just create a separate NSManagedObjectContext for your asyncTask? They are cheap.
-Heath Borders heath.bord...@gmail.com Twitter: heathborders http://heath-tech.blogspot.com On Tue, Mar 29, 2011 at 4:38 PM, Steve Mykytyn <smyky...@gmail.com> wrote: > countForFetchRequest seems to bog down on really big collections of > entities. For approx 170K entities it takes around 10 seconds on an iPhone > 3GS to count them, which is a problem in a UITableView where you are trying > to display a list of entities and associated counts. > > A GCD based solution, that queues up countForFetchRequest on a concurrent > queue for each entity, and then updates the corresponding cell when > finished, seems to work pretty well, although one or two big entity counts > essentially bog down all the requests behind them. Counts are cached so > that countForFetchRequest is only called once for any entity. > > Code below, can anyone suggest any further optimization or different > approaches that might be more effective? > > (I'm aware of the danger of multi-threading core data - this particular > managed object context never changes and nothing is happening to it on other > threads when this read is going on) > > - (void) countEntitiesNamed:(NSString *)entityName > inContext:(NSManagedObjectContext *)context forIndexPath:(NSIndexPath > *)indexPath { > > NSNumber *rowCountObject = [self.rowCountMD valueForKey:entityName]; > > if (rowCountObject) return; > > // > http://www.mikeash.com/pyblog/friday-qa-2009-08-28-intro-to-grand-central-dispatch-part-i-basics-and-dispatch-queues.html > > dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, > 0), ^{ > > NSEntityDescription *ed; > NSFetchRequest *frq; > > frq = [[[NSFetchRequest alloc] init] autorelease]; > ed = [NSEntityDescription entityForName:entityName > inManagedObjectContext:context]; > [frq setEntity:ed]; > NSDate *startDate = [NSDate date]; > NSUInteger rowCount = [context countForFetchRequest:frq error:nil]; > NSTimeInterval timeInterval = -[startDate timeIntervalSinceNow]; > DLog(@"%0.2lf seconds for %d %@ ",timeInterval,rowCount,entityName); > > dispatch_async(dispatch_get_main_queue(), ^{ > [rowCountMD setValue:[NSNumber numberWithInteger:rowCount] > forKey:entityName]; > UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath]; > cell.detailTextLabel.text = [NSString stringWithFormat:@"%@ objects", > [NSNumberFormatter localizedStringFromNumber:[NSNumber > numberWithInteger:rowCount] > numberStyle:NSNumberFormatterDecimalStyle]]; > > }); > }); > > > } > _______________________________________________ > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/cocoa-dev/heath.borders%40gmail.com > > This email sent to heath.bord...@gmail.com > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
