Process States and the Process State Graph
- a program in execution (simple definition)
- a process is an active entity, while a program is a static entity
- at most one process can be running on the CPU (or a single processor in a multiprocessor machine) at one time
- Each process is in exactly one of the following states at each instant of time:
- New: The process is being created
- Running: Instructions are being executed.
- Waiting: The process is waiting for some event to occur (such as an I/O completion)
- Ready: The process is ready to execute, but it must wait to be assigned to the processor
- Terminated: The process has finished execution.
- The process state graph is a conceptual model of how a process can change states.
- It does not correspond directly to a data structure in the operating system.
- It shows the valid changes that can be made to the process state and when these changes are made.
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