A monitor is a collection of procedures, variables, and data structures that are all grouped together in a special kind of module or package.

Processes may call the procedures in a monitor whenever they want to, but they cannot directly access the monitor's internal data structures from procedures declared outside the monitor. Figure shows illustrates a monitor written in an imaginary language, Pidgin Pascal. C cannot be used here because monitors are a language concept and C does not have them.

Monitor example

      integer /;

      condition c;

      procedure producer();





      procedure consumer (); 



      end monitor;