上海交通大学：《操作系统 Operating System》课程教学资源（课件讲稿）OS-process_Lec8

OPERATING SYSTEMS 1 龚玲 lgong@sjtu.edu.cn

OPERATING SYSTEMS 龚玲 lgong@sjtu.edu.cn 1

REVIEW o Communication in Client-Server Systems o http://wenku.baidu.com/course/study/77fldcccda38376ba flfae94#665ea0c7aa00b52acfc7ca94

REVIEW  Communication in Client-Server Systems  http://wenku.baidu.com/course/study/77f1dcccda38376ba f1fae94#665ea0c7aa00b52acfc7ca94

CHAPTER 4:THREADS Operating System Concepts with Java-7th Edition,Nov 15,2006 Silberschatz,Galvin and Gagne 2007

Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Silberschatz, Galvin and Gagne ©2007 CHAPTER 4: THREADS

CHAPTER 4:THREADS o Overview o Multithreading Models o Threading Issues o Pthreads o Windows XP Threads o Linux Threads o Java Threads

CHAPTER 4: THREADS  Overview  Multithreading Models  Threading Issues  Pthreads  Windows XP Threads  Linux Threads  Java Threads

GOALS FOR TODAY o Why introduce thread? o What is the concept of thread?

GOALS FOR TODAY  Why introduce thread?  What is the concept of thread?

MOTIVATION APPLICATION EXAMPLES o Air ticketing system:dealing with several requests from the ticket windows at the same time. o Database software:dealing with several data requests from the clients. Operating system:dealing with multi requests for reading disk from several users. o Same situation:multi requests based on same data sections o Please design your solutions using process model and analyze the performance of your solutions

MOTIVATION APPLICATION EXAMPLES  Air ticketing system: dealing with several requests from the ticket windows at the same time.  Database software: dealing with several data requests from the clients.  Operating system: dealing with multi requests for reading disk from several users.  Same situation: multi requests based on same data sections  Please design your solutions using process model and analyze the performance of your solutions

SOLUTION 1: o Use one process to deal with all the requests in order o Shortcomings: long waiting slow response lack of efficiency

SOLUTION 1:  Use one process to deal with all the requests in order  Shortcomings:  long waiting  slow response  lack of efficiency

SOLUTION 2: o Use one process to deal with all the requests concurrently o Shortcomings: Increase the process's burden and complexity very hard to implement

SOLUTION 2:  Use one process to deal with all the requests concurrently  Shortcomings:  Increase the process’s burden and complexity  very hard to implement

SOLUTION 3: use several independent processes,each one handles one request o Shortcomings: need a lot of processes which use the same resource build the processes frequently switch the processes frequently huge overhead o Analysis the management information of the processes are similar the works of switching between the processes are similar

SOLUTION 3:  use several independent processes, each one handles one request  Shortcomings:  need a lot of processes which use the same resource  build the processes frequently  switch the processes frequently  huge overhead  Analysis  the management information of the processes are similar  the works of switching between the processes are similar

NEW SOLUTION o deal with requests concurrently (avoid shortcomings of solution 1) o OS should take charge of the management (avoid shortcomings of solution 2) o low overhead(avoid shortcomings of solution 3)

NEW SOLUTION  deal with requests concurrently (avoid shortcomings of solution 1)  OS should take charge of the management (avoid shortcomings of solution 2)  low overhead(avoid shortcomings of solution 3)