Bài giảng hệ điều hành nâng cao chapter 4 threads

Chapter 4: Threads

Operating System Concepts – 8

th

Edition

Silberschatz, Galvin and Gagne ©2009


Chapter 4: Threads
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Overview

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Multithreading Models

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Thread Libraries

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Threading Issues

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Operating System Examples

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Windows XP Threads

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Linux Threads

Operating System Concepts – 8

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Edition

4.2

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Objectives
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To introduce the notion of a thread — a fundamental unit of CPU utilization that forms the basis of multithreaded computer systems

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To discuss the APIs for the Pthreads, Win32, and Java thread libraries

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To examine issues related to multithreaded programming

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Motivation
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Threads run within application

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Multiple tasks with the application can be implemented by separate threads

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Update display

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Fetch data

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Spell checking

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Answer a network request

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Process creation is heavy-weight while thread creation is light-weight

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Can simplify code, increase efficiency

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Kernels are generally multithreaded

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Single and Multithreaded Processes

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Benefits
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Responsiveness

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Resource Sharing

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Economy

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Scalability

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Multicore Programming
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Multicore systems putting pressure on programmers, challenges include:

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Dividing activities

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Balance

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Data splitting

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Data dependency

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Testing and debugging

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Multithreaded Server Architecture

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4.8

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Concurrent Execution on a
Single-core System

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4.9

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Parallel Execution on a
Multicore System

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4.10

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User Threads
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Thread management done by user-level threads library

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Three primary thread libraries:

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POSIX Pthreads

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Win32 threads

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Java threads

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4.11

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Kernel Threads
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Supported by the Kernel

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Examples

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Windows XP/2000

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Solaris

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Linux

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Tru64 UNIX

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Mac OS X

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4.12

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Multithreading Models
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Many-to-One

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One-to-One

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Many-to-Many

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Many-to-One
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Many user-level threads mapped to single kernel thread

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Examples:

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Solaris Green Threads

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GNU Portable Threads

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Many-to-One Model

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One-to-One
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Each user-level thread maps to kernel thread

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Examples

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Windows NT/XP/2000

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Linux

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Solaris 9 and later

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One-to-one Model

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Many-to-Many Model

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Allows many user level threads to be mapped to many kernel threads

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Allows the operating system to create a sufficient number of kernel threads

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Solaris prior to version 9

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Windows NT/2000 with the ThreadFiber package

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Many-to-Many Model

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Two-level Model

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Similar to M:M, except that it allows a user thread to be bound to kernel thread

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Examples

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IRIX

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HP-UX

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Tru64 UNIX

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Solaris 8 and earlier

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Two-level Model

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4.21

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Thread Libraries
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Thread library provides programmer with API for creating and managing threads

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Two primary ways of implementing

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Library entirely in user space

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Kernel-level library supported by the OS

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Pthreads
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May be provided either as user-level or kernel-level

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A POSIX standard (IEEE 1003.1c) API for thread creation and synchronization

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API specifies behavior of the thread library, implementation is up to development of the library

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Common in UNIX operating systems (Solaris, Linux, Mac OS X)

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4.23

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Pthreads Example

Operating System Concepts – 8

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4.24

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Pthreads Example (Cont.)

Operating System Concepts – 8

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4.25

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