RestKit Performance and Core Data

Question

RestKit performance is unacceptably slow when downloading just shy of 9,000 objects — it's taking 10 minutes on the simulator, and indefinite time on an iPad Mini.

I have several tables I'm downloading from a restful interface. It all works, but there appears to be an exponential scale problem that becomes intolerable when there are many objects. The following table has the most problems:

optionMapping.identificationAttributes = @[@"optionID"];

// OptionType
RKEntityMapping *optionTypeMapping = [RKEntityMapping mappingForEntityForName:@"OptionType" inManagedObjectStore:rkMOS];
[optionTypeMapping addAttributeMappingsFromDictionary:@{
 @"id" : @"optionTypeID",
 @"option_type" : @"optionType",}];

optionTypeMapping.identificationAttributes = @[@"optionTypeID"];

The attribute optionTypeID is indexed in Core Data, and is not optional.

There are some relationships to other tables, which I map as follows:

// Option.optionType -> OptionType

[optionMapping addConnectionForRelationship:@"optionType" connectedBy: @"optionTypeID"];

// Option.unit -> Unit

[optionMapping addConnectionForRelationship:@"unit" connectedBy:@"unitID"];

These don't seem to be the problem -- I commented them out, and the download is still very, very slow.

I set up a response descriptor (this is a catalog, so I only need to download it). Note that the following code shows a setup for all of the tables.

NSArray *reqA = @[@{@"endpoint" : API_VENDORS_ENDPOINT,
                    @"mapping" : vendorMapping},

                  @{@"endpoint" : API_OPTION_TYPES_ENDPOINT,
                    @"mapping" : optionTypeMapping},

                  @{@"endpoint" : API_OPTIONS_ENDPOINT,
                    @"mapping" : optionMapping},

                  @{@"endpoint" : API_UNITS_ENDPOINT,
                    @"mapping" : unitMapping},

                  @{@"endpoint" : API_PRICE_TIERS_ENDPOINT,
                    @"mapping" : priceTierMapping},

                  @{@"endpoint" : API_PRODUCT_TYPES_ENDPOINT,
                    @"mapping" : productTypeMapping},

                  @{@"endpoint" : API_PRODUCTS_ENDPOINT,
                    @"mapping" : productMapping}
                  ];

for (NSDictionary *mapD in reqA) {

    RKResponseDescriptor *thisRD = [RKResponseDescriptor
                                    responseDescriptorWithMapping:[mapD valueForKey:@"mapping"]
                                    pathPattern:[mapD valueForKey:@"endpoint"]
                                    keyPath:nil
                                    statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

    [_objMgr addResponseDescriptor:thisRD];

I'm using the object manager to download the table:

[_objMgr getObjectsAtPath:verbStr
              parameters:nil
                 success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                     RKLogInfo(@"%@ load complete: %@", verbStr, [NSDate date]);

                     NSInteger idx = [loadA indexOfObject:verbStr] + 1;

                     if (idx < [loadA count]) {
                         [self load:[loadA objectAtIndex:idx] stack:loadA];
                     }

                     [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:verbStr];
                     [[NSUserDefaults standardUserDefaults] synchronize];

                     NSDictionary *options = @{@"verb" : verbStr};
                     [[NSNotificationCenter defaultCenter] postNotificationName:OBJECTS_DOWNLOADED object:self userInfo:options];

                 } failure:^(RKObjectRequestOperation *operation, NSError *error) {
                     RKLogError(@"Load failed with error: %@", error);

                     NSInteger statusCode = operation.HTTPRequestOperation.response.statusCode;

                     if (401 == statusCode) {
                         [self resetAdmin];
                     }
                 }];

The console output shows that mapping is chugging along, but it takes forever. The following is just one snippet from thousands like it:

2013-08-01 17:11:49.319 CarpetDirect[138:1507] D restkit.object_mapping:RKMappingOperation.m:952 Starting mapping operation...
2013-08-01 17:11:49.321 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:953 Performing mapping operation: <RKMappingOperation 0x1dda2160> for 'Option' object. Mapping values from object {
   id = 1307;
   "option_type" = 0;
   unit = "<null>";
   value = "939 Puddle";
} to object <Option: 0x1dd55020> (entity: Option; id: 0x1dd55060 <x-coredata:///Option/t3ABD9C1C-1BBA-4C39-AEF7-EB3D1D9AFC0B1334> ; data: {
   optionID = 1307;
   optionType = nil;
   optionTypeID = 0;
   orderedItems =     (
);
   products =     (
);
   unit = nil;
   unitID = 0;
   value = nil;
}) with object mapping (null)
2013-08-01 17:11:49.324 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:550 Mapping attribute value keyPath 'id' to 'optionID'
2013-08-01 17:11:49.326 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:583 Skipped mapping of attribute value from keyPath 'id to keyPath 'optionID' -- value is unchanged (1307)
2013-08-01 17:11:49.329 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:550 Mapping attribute value keyPath 'unit' to 'unitID'
2013-08-01 17:11:49.333 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:431 Found transformable value at keyPath 'unit'. Transforming from type 'NSNull' to 'NSNumber'
2013-08-01 17:11:49.334 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:572 Mapped attribute value from keyPath 'unit' to 'unitID'. Value: (null)
2013-08-01 17:11:49.336 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:550 Mapping attribute value keyPath 'value' to 'value'
2013-08-01 17:11:49.338 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:572 Mapped attribute value from keyPath 'value' to 'value'. Value: 939 Puddle
2013-08-01 17:11:49.339 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:550 Mapping attribute value keyPath 'option_type' to 'optionTypeID'
2013-08-01 17:11:49.342 CarpetDirect[138:1507] T restkit.object_mapping:RKMappingOperation.m:583 Skipped mapping of attribute value from keyPath 'option_type to keyPath 'optionTypeID' -- value is unchanged (0)
2013-08-01 17:11:49.345 CarpetDirect[138:1507] D restkit.object_mapping:RKMappingOperation.m:1021 Finished mapping operation successfully...
2013-08-01 17:11:49.348 CarpetDirect[138:1507]

Any ideas on how I can speed this up? All I want to do is blast the data down from the server to Core Data.

Answer 1

Hard to say much without more context, but what are your RestKit logging options? From my experience, mapping logging in RestKit is very verbose, slowing things down by the factor of 10x.

Disable all RestKit logging, and see if anything has improved. Then, if there still is a problem, use Instruments to profile your application - you should easily see which code paths are taking most of the time (parsing, RestKit mapping, Core Data etc.)