Chapter 4 : Process and Threads

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Chapter 4 : Process and Threads by Mind Map: Chapter 4 : Process and Threads

1. 1.Process

1.1. *A program in execution

1.2. *An instance of a running program

1.3. *The entity that can be assigned to, and executed on, a processor

1.4. *A unit of activity characterized by a single sequential thread of execution, a current state, and an associated set of system resources

2. 4.Process States

2.1. *Trace

2.1.1. *The behavior of an individual process by listing the sequence of instructions that execute for that process

2.1.2. *The behavior of the processor can be characterized by showing how the traces of the various processes are interleaved

2.2. *Dispatcher

2.2.1. *Small program that switches the processor from one process to another

3. Pogram

3.1. *Passive entity such as contents of a file stored disk.

4. Process

4.1. *Active entity with a program counter specifying the next instruction to be execute .

5. 2.Process Elements

5.1. *Program code

5.1.1. Which may be shared with other process that are executing the same program

5.2. *A set of data associated with the code

5.2.1. when the processor begins to execute the program, refer to executing entity as a proces

6. 3.Process Control block

6.1. *Contains the process elements

6.2. *It is possible to interrupt a running process and latter resume execution as if the interruption had not occurred

6.3. *Created & manage by the operating system

6.4. *Key tool that allows support for multilple process

7. 5.Two-State Process Model

7.1. *Running

7.2. *Not-running

8. 6.Process Creation

8.1. *Process Spawning

8.1.1. *When th OS creates a process at the explicit request of another process

8.2. *Parent process

8.2.1. *Is the original, creating, process

8.3. *Child Process

8.3.1. *IS the new process

9. 7.Process Termination

9.1. *There must be a means for a process to indicates its completition

9.2. *A batch job should include a HALT instruction or an explicit OS service call for terminantion

9.3. *For an interactive application, the action of the user will indicate when the process is complete

10. 8.Fve-State Process Model

10.1. *New

10.1.1. *A process is being created

10.2. *Ready

10.2.1. *A process that is prepared to be executed when given chance

10.3. *Blocked

10.3.1. *A process that cannot execute until some events occurs, such as I/O completion

10.4. *Running

10.4.1. *A process that is currently being executed

10.5. *Exit

10.5.1. *A process that has finished its execute

10.6. 9.Suspended Process

10.6.1. *Suspend *A process that has been swapped out of main memory

11. 10.Characteristics of a Suspended Process

11.1. *The process is not immediately available for execution

11.2. *The process may or may not be waiting on an event

11.3. *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

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

12. 11.Process and Threads

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

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

12.3. *Multi threading - The ability of an OS to support multiple, concurrent paths of execution within a single process

13. Threads

13.1. *A basic unit of CPU utilization

14. 12.Single Threaded Approaches

14.1. *A single thread of execution per process, in which the concept of a thread is not recognized, is referred to as a single-threaded approach

14.2. *MS-DOS is an example

15. 13.Multithreaded Approaches

15.1. *The right half of multithreaded approaches

15.2. *A Java run-time environment is an example of a system of one process with multiple threads

16. Benefits of Threads

16.1. *Takes less time to create a new thread than a process

16.2. *Less time to terminate a thread than a process

16.3. *Switching between two threads takes less time than switching between processes

16.4. *Threads enhance efficiency in communication between programs

17. 14.Operating System Control Structures

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

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

17.3. *Four different types of tables maintained by the OS:

17.3.1. *Memory tables

17.3.2. *IO Tables

17.3.3. *File Tables

17.3.4. *Process Tables