describe the life circle of process and  why each process must have one PCB.

A process is a dynamic entity,from creation to extinction,which is the entire life cycle of a process. Process possible

Will experience a variety of different states,generally there are three states.

Ready state: The process has obtained all other resources except cpu,waiting for cpu scheduling in the ready queue

Execution status: The cpu has been obtained and all required resources are running

blocking state (waiting state): The process abandons the processor or waits for the required resources

I don’t own the processor,and other resources are not met.

State transition: When the process in the ready state gets cpu scheduling,it will become the execution state.

If you sleep or wait for a certain resource,it will become a wait state. If the time is up,the process will be heavy.

The new ready state is placed at the end of the ready queue,and the process waiting for the state gets resources other than cpu Will become ready

Process Contro1 B1ock (PCB)is a data structure used to record process status and other related information. PCB is the only sign of the existence of the process.

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