What is a process, process tree, address space?

Here are some points which are useful in understanding process, process tree, and address space:

1) A program is an instance of a program in execution.

2) A process has the information which is required to run a program.

3) Information which is related to processes is stored in a process table.

4) When a process is suspended, related pointers which can be used to restart the process is saved by the operating system. A suspended process has the address space and its entry in process table.

5) Communication between processes is known as inter process communication.

6) Process tree: A process can create more processes. These created processes are arranged in a tree hierarchy and are known as child processes.

7) A process has a UID (User Identification) of the user who started the process.

8) A process is an abstraction of a program which is running.

9) A process is used for concurrent operations in a single CPU.

10) By using a process a physical CPU is converted to many virtual CPUs.

11) Address space: Every process has an address space which is a list of memory locations from 0 to a maximum value. A process can read and write in this address space. For a computer which has 64 bit address, then address space would be 2 pow(64) bytes.

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