Xcode Instruments

Usage101

Eugene Solodovnykovhttp://idevblog.info

@sharpland

Instruments app purpose

Track down difficult-to-reproduce problems in your code

Do performance analysis on your program

Automate testing of your code

Stress-test parts of your application

Perform general system-level troubleshooting

Gain a deeper understanding of how your code works

Base templates

Leaks

Uses console leaks application (man leaks will explain you everything)

A lot of applications contain leaks. Our target is to avoid leaks in our applications :)

Quick example – Droplr application

Allocations

Count each allocation in your application’s session

May help with memory leaks even if Leaks instrument doesn’t see them

Quick example – Hex Fiend application

Hex Fiend dissection

Choose Hex Fiend application as a target

Run Leaks and Allocations instruments

Create a new window and close it (5-7 times)

Leaks just keep silence while Allocations instrument displays constant chart growth

Problem analyzing

Yeah, it’s difficult

Use heapshots

- init { [super init]; lineCountingRepresenter = [[HFLineCountingRepresenter alloc] init]; hexRepresenter = [[HFHexTextRepresenter alloc] init]; asciiRepresenter = [[HFStringEncodingTextRepresenter alloc] init]; scrollRepresenter = [[HFVerticalScrollerRepresenter alloc] init]; layoutRepresenter = [[HFLayoutRepresenter alloc] init]; //is missed in representers statusBarRepresenter = [[HFStatusBarRepresenter alloc] init]; dataInspectorRepresenter = [[DataInspectorRepresenter alloc] init]; [[hexRepresenter view] setAutoresizingMask:NSViewHeightSizable]; [[asciiRepresenter view] setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable]; ... return self;}

- (NSArray *)representers { return [NSArray arrayWithObjects:lineCountingRepresenter, hexRepresenter, asciiRepresenter, scrollRepresenter, dataInspectorRepresenter, statusBarRepresenter, nil];}

- (void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; [[self representers] makeObjectsPerformSelector:@selector(release)];

...

[super dealloc];}

And leaks won’t detect it

Time Profiler

Periodically stops the app and records the stack trace.

Allows to determine where execution time was spent

Can we do more?

Different pre-defined instruments

DTrace-based custom instruments

Mix them!

To be continued...