Instruments is an application performance analyzer and visualizer, integrated in Xcode 3.0

Xcode

Xcode is a suite of tools, developed by Apple, for developing software for Mac OS X and iOS. Xcode 4.2, the latest major version, is available on the Mac App Store for free for Mac OS X 10.7 , and on the Apple Developer Connection website for free to registered developers Xcode is a suite of tools,...

 and later versions of Xcode. It is a developer tool included in Apple Mac OS X v10.5

Mac OS X v10.5

Mac OS X Leopard is the sixth major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers. Leopard was released on 26 October 2007 as the successor of Tiger , and is available in two variants: a desktop version suitable for personal computers, and a...

 and later versions of Mac OS X, built on top of the DTrace

DTrace

DTrace is a comprehensive dynamic tracing framework created by Sun Microsystems for troubleshooting kernel and application problems on production systems in real time...

  tracing

Tracing (software)

In software engineering, tracing is a specialized use of logging to record information about a program's execution. This information is typically used by programmers for debugging purposes, and additionally, depending on the type and detail of information contained in a trace log, by experienced...

  framework

Software framework

In computer programming, a software framework is an abstraction in which software providing generic functionality can be selectively changed by user code, thus providing application specific software...

 from OpenSolaris

OpenSolaris

OpenSolaris was an open source computer operating system based on Solaris created by Sun Microsystems. It was also the name of the project initiated by Sun to build a developer and user community around the software...

 and ported

Porting

In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed...

 to Mac OS X

Mac OS X

Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

.

Instruments shows a time line displaying any event occurring in the application, such as CPU activity variation, memory allocation, and network and file activity, together with graphs and statistics. Group of events are monitored via customizable "instruments", which have the ability to record user generated events and replay (emulate) them exactly as many times as needed, so a developer can see the effect of code changes without actually doing the repetitive work. The Instrument Builder feature allows the creation of custom analysis instruments.

Built-in instruments can track

• User events, such as keyboard
  Keyboard (computing)
  In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
  
   keys pressed and mouse moves and clicks with exact time.
• CPU
  Central processing unit
  The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
  
   activity of processes
  Process (computing)
  In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
  
   and threads
  Thread (computer science)
  In computer science, a thread of execution is the smallest unit of processing that can be scheduled by an operating system. The implementation of threads and processes differs from one operating system to another, but in most cases, a thread is contained inside a process...
  
  .
• Memory allocation and release, garbage collection
  Garbage collection (computer science)
  In computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
  
   and memory leak
  Memory leak
  A memory leak, in computer science , occurs when a computer program consumes memory but is unable to release it back to the operating system. In object-oriented programming, a memory leak happens when an object is stored in memory but cannot be accessed by the running code...
  
  s.
• File
  Computer file
  A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
  
   reads, writes, locks.
• Network activity and traffic.
• Graphics and inner workings of OpenGL
  OpenGL
  OpenGL is a standard specification defining a cross-language, cross-platform API for writing applications that produce 2D and 3D computer graphics. The interface consists of over 250 different function calls which can be used to draw complex three-dimensional scenes from simple primitives. OpenGL...
  
  .