Final answer:
Condition variables must be declared and used within a monitor in order to enable a process to wait.
Step-by-step explanation:
To enable a process to wait within the monitor, condition variables must be declared and used. Condition variables are used to synchronize the execution of threads and allow them to wait for certain conditions before proceeding. They are typically used in conjunction with a mutex or lock to provide mutual exclusion.
Condition variables work by allowing threads to block and wait for a particular condition to be true. When the condition becomes true, another thread can signal the condition variable, waking up the waiting thread. This allows for efficient and synchronized thread communication and coordination within a monitor.
For example, imagine a producer-consumer scenario where multiple threads are producing and consuming items from a shared buffer. The producer threads can wait on a condition variable, waiting for the buffer to have available space before they can produce a new item. The consumer threads can also wait on a condition variable, waiting for the buffer to have items before they can consume. The condition variables ensure that the producer and consumer threads coordinate their actions and avoid race conditions.