Operating Systems: Concurrent and Distributed Software Design

4.3. Process state

The discussion of Section 4.2 highlights that a process may be in a number of distinct states, illustrated in Figure 4.3:

• running on a processor: RUNNING state;

• able to run on a processor: RUNNABLE state;

• unable to run on a processor because it is awaiting some event and cannot proceed until that event arrives: BLOCKED state.

Figure 4.3. States and state transitions of a process.

The transition from running to runnable occurs when the process does not voluntarily give up its processor (by asking to be blocked while waiting for an event to occur) but is forcibly preempted from its processor either because it has used up its allotted ...