Instruments (application)

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Instruments (formerly Xray) is an application performance analyzer and visualizer, integrated in Xcode 3.0. It is a developer tool from Apple Inc. Mac OS X v10.5, built on top of the DTrace tracing framework from OpenSolaris and ported to Mac OS X.

Instruments shows a time line of any events in application and graphs of statistics and events such as CPU, network and file activity, and memory allocation. Different events are monitored by "instruments", each of which track a handful of events and can be customized. They are also capable of recording user generated events and replaying (emulating) them exactly several times, so a developer can see the effect of his code changes without tedious clicking. The Instrument Builder feature allows creation of custom analysis instruments.

Built-in instruments can track

User events, such as keyboard keys pressed and mouse moves and clicks with exact time.
CPU activity of processes and threads.
Memory allocation and releasing of memory regions, garbage collection, and memory leaks.
File reads, writes, locks.
Network activity and traffic.
Graphics and inner workings of OpenGL.

[edit] Issues

Instruments monitoring disk activity will fail with the error "Could not locate DTrace Server" unless the "Developer Tools System Components" package from the CD is also installed.