iPhone Development (performance-analysis application)

Shark

Shark is a performance-analysis application that creates a time-based profile of your program’s execution; over a given period it traces function calls and graphs memory allocations. You can use Shark to track information for a single program or for the entire system, which on Mac OS X includes kernel components such as drivers and kernel extensions. Shark also monitors file-system calls, traces system calls and memory allocations, performs static analyses of your code, and gathers information about cache misses, page faults, and other system metrics. Shark supports the analysis of code written in C, Objective-C, C++, and other languages.

Other Performance Applications (Mac OS X)

Many applications are used in measuring and analyzing aspects of a Mac OS X program’s performance. They are located in <Xcode>/Applications/Performance Tools.

• Thread Viewer displays activity among a process’s threads. It shows time lines of activity on each thread, which is color-coded with the action. By clicking a time line, you can get a sample backtrace of activity at that point.

• BigTop graphs performance trends over time, providing a real-time display of memory usage, page faults, CPU usage, and other data.

• Spin Control automatically samples unresponsive applications. You leave Spin Control running in the background while you launch and test your applications. If applications become unresponsive to the point where the spinning cursor appears, Spin Control automatically samples your application to gather information about what your application was doing during that time.

• MallocDebug shows all currently allocated blocks of memory in your program, organized by the call stack at the time of allocation. At a glance you can see how much allocated memory your application consumes, where that memory was allocated from, and which functions allocated large amounts of memory. MallocDebug can also find allocated memory that is not referenced elsewhere in the program, thus helping you find leaks and track down exactly where the memory was allocated.

• QuartzDebug is a tool to help you debug how your application displays itself. It is especially useful for applications that do significant amounts of drawing and imaging. QuartzDebug has several debugging options, including the following:

  • Auto-flush drawing, which flushes the contents of graphics contexts after each drawing operation)

  • A mode that paints regions of the screen in yellow just before they’re updated

  • An option that takes a static snapshot of the system-wide window list, giving the owner of each window and how much memory each window consumes.

For performance analysis, you can also use command-line tools such as:

• top, which shows a periodically sampled set of statistics on currently running processes

• gprof, which produces an execution profile of a program

• fs_usage, which displays file-system access statistics

Many other command-line tools for performance analysis and other development tasks are available. Some are located in /usr/bin and /usr/sbin, and some Apple-developed command-line tools are installed in <Xcode>/Tools. For many of these tools you can consult their manual page for usage information. (To do this, either choose Help > Open man page in Xcode or type man followed by the name of the tool in a Terminal shell.)

Further Reading: For more on the performance tools and applications you can use in Cocoa application development, as well as information on concepts, techniques, guidelines, and strategy related to performance, see Performance Overview. Cocoa Performance Guidelines