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monitors

_ High-level synchronization construct that allows the safe sharing

of an abstract data type among concurrent processes.

monitor monitor-name

 {

     shared variable declarations

         procedure body P1 (…) {

             . . .

  }

         procedure body P2 (…) {

              . . .

 }

          procedure body Pn (…) {

              . . .

  }

{

             initialization code

}

}

Condition Variables

To allow a process to wait within the monitor, a condition variable must be declared, as condition x, y;

_ Condition variable can only be used with the operations wait and signal.

? The operation

          x.wait();

means that the process invoking this operation is suspended until another process invokes

          x.signal();

? The x.signal operation resumes exactly one suspended process. If no process is suspended,

    then the signal operation has no effect.