This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. The OS must allocate resources to processes, enable processes to share and exchange information, what is process management in operating system pdf the resources of each process from other processes and enable synchronization among processes.
To meet these requirements, the OS must maintain a data structure for each process, which describes the state and resource ownership of that process, and which enables the OS to exert control over each process. With some programs, it is possible to have one copy loaded into memory, while several users have shared access to it so that they each can execute the same program-code.
Such a program is said to be re-entrant. The processor at any instant can only be executing one instruction from one program but several processes can be sustained over a period of time by assigning each process to the processor at intervals while the remainder become temporarily inactive. A number of processes being executed over a period of time instead of at the same time is called concurrent execution.