Process and Threads

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Process and Threads by Mind Map: Process  and Threads

1. Process

1.1. Active entity with a program counter specifying the next instruction.

1.2. Process Control Block

1.2.1. Contians the process elements

1.2.2. it is possible to interrupt a running process and later resume execution as if the interruption had not occurred.

1.2.3. Created and managed by the operating system.

1.2.4. Key tool that allows support for multiple process.

2. Process States

2.1. Two-State Process Model

2.1.1. A process may be in one of two states: -Running -Not Running

2.2. Creation

2.2.1. Occurs when a new process is to e added to those currently being managed process

2.2.2. The operating system builds the data structures that are used to managed the process and allocates address space in main memory to the process.

2.2.3. process spawning

2.2.3.1. When the OS creates a process at the explicit request of another process

2.3. Termination

2.3.1. There must be a means for a process to indicate its complettion

2.3.2. A batch job should include a HALT instruction or an explicit OS service call for termination

2.4. Five-State Model

2.5. Suspended Processes

2.5.1. The process is not immediately available for execution

2.5.2. The process was placed in a suspended state by an agent :either itself, a parent process,or the OS ,for the purpose of preventing its execution

2.5.3. The process may or may not be waiting on an event

2.5.4. The process may not be removed from this state until the agent explicitly orders the removal

3. Pocesses and Threads

3.1. The unit of dispatching is referred to as a thread or lightweight process

3.2. The unit of resource ownership is referred to as a process or task

3.3. Multithreading- the ability of an OS to support multiple, concurrent paths of execution within a single process

4. Operating System Control Structures

4.1. To manage processes and resources, OS must have information about the current status of each process and resource.

4.2. The OS constructs and maintains tables of information about each entity that it is managing .

4.3. Four different type of maintained by the OS

4.3.1. Memory tables

4.3.2. IO tables

4.3.3. File tables

4.3.4. Proocess tables