When writing both applications programs and systems programs it is sometimes necessary to monitor memory usage (e.g., for leaks) and/or CPU usage (e.g., for bottlenecks). All operatings systems have some tools that can perform basic monitoring.

Press Ctrl+Alt+Del and click on the Task List button.

Run the “Activity Monitor” (e.g., ⌘+Spacebar, enter “Activity Monitor” in Spotlight, and click on “Activity Monitor”).

From the command line, run top (and type Q when done).

In Gnome, run the gnome-system-monitor.