Chapter 4 Threads Chapter 4 Threads n Overview

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Chapter 4: Threads

Chapter 4: Threads

Chapter 4: Threads n Overview n Multithreading Models n Threading Issues n Pthreads n

Chapter 4: Threads n Overview n Multithreading Models n Threading Issues n Pthreads n Windows XP Threads n Linux Threads n Java Threads Operating System Concepts 4. 2 Silberschatz, Galvin and Gagne © 2005

Single and Multithreaded Processes Operating System Concepts 4. 3 Silberschatz, Galvin and Gagne ©

Single and Multithreaded Processes Operating System Concepts 4. 3 Silberschatz, Galvin and Gagne © 2005

Benefits n Responsiveness n Resource Sharing n Economy n Utilization of MP Architectures Operating

Benefits n Responsiveness n Resource Sharing n Economy n Utilization of MP Architectures Operating System Concepts 4. 4 Silberschatz, Galvin and Gagne © 2005

User Threads n Thread management done by user-level threads library n Three primary thread

User Threads n Thread management done by user-level threads library n Three primary thread libraries: l POSIX Pthreads l Win 32 threads l Java threads Operating System Concepts 4. 5 Silberschatz, Galvin and Gagne © 2005

Kernel Threads n Supported by the Kernel n Examples l Windows XP/2000 l Solaris

Kernel Threads n Supported by the Kernel n Examples l Windows XP/2000 l Solaris l Linux l Tru 64 UNIX l Mac OS X Operating System Concepts 4. 6 Silberschatz, Galvin and Gagne © 2005

Multithreading Models n Many-to-One n One-to-One n Many-to-Many Operating System Concepts 4. 7 Silberschatz,

Multithreading Models n Many-to-One n One-to-One n Many-to-Many Operating System Concepts 4. 7 Silberschatz, Galvin and Gagne © 2005

Many-to-One n Many user-level threads mapped to single kernel thread n Examples: l Solaris

Many-to-One n Many user-level threads mapped to single kernel thread n Examples: l Solaris Green Threads l GNU Portable Threads Operating System Concepts 4. 8 Silberschatz, Galvin and Gagne © 2005

Many-to-One Model Operating System Concepts 4. 9 Silberschatz, Galvin and Gagne © 2005

Many-to-One Model Operating System Concepts 4. 9 Silberschatz, Galvin and Gagne © 2005

One-to-One n Each user-level thread maps to kernel thread n Examples l Windows NT/XP/2000

One-to-One n Each user-level thread maps to kernel thread n Examples l Windows NT/XP/2000 l Linux l Solaris 9 and later Operating System Concepts 4. 10 Silberschatz, Galvin and Gagne © 2005

One-to-one Model Operating System Concepts 4. 11 Silberschatz, Galvin and Gagne © 2005

One-to-one Model Operating System Concepts 4. 11 Silberschatz, Galvin and Gagne © 2005

Many-to-Many Model n Allows many user level threads to be mapped to many kernel

Many-to-Many Model n Allows many user level threads to be mapped to many kernel threads n Allows the operating system to create a sufficient number of kernel threads n Solaris prior to version 9 n Windows NT/2000 with the Thread. Fiber package Operating System Concepts 4. 12 Silberschatz, Galvin and Gagne © 2005

Many-to-Many Model Operating System Concepts 4. 13 Silberschatz, Galvin and Gagne © 2005

Many-to-Many Model Operating System Concepts 4. 13 Silberschatz, Galvin and Gagne © 2005

Two-level Model n Similar to M: M, except that it allows a user thread

Two-level Model n Similar to M: M, except that it allows a user thread to be bound to kernel thread n Examples l IRIX l HP-UX l Tru 64 UNIX l Solaris 8 and earlier Operating System Concepts 4. 14 Silberschatz, Galvin and Gagne © 2005

Two-level Model Operating System Concepts 4. 15 Silberschatz, Galvin and Gagne © 2005

Two-level Model Operating System Concepts 4. 15 Silberschatz, Galvin and Gagne © 2005

Threading Issues n Semantics of fork() and exec() system calls n Thread cancellation n

Threading Issues n Semantics of fork() and exec() system calls n Thread cancellation n Signal handling n Thread pools n Thread specific data n Scheduler activations Operating System Concepts 4. 16 Silberschatz, Galvin and Gagne © 2005

Thread Cancellation n Terminating a thread before it has finished n Two general approaches:

Thread Cancellation n Terminating a thread before it has finished n Two general approaches: l Asynchronous cancellation terminates the target thread immediately l Deferred cancellation allows the target thread to periodically check if it should be cancelled Operating System Concepts 4. 17 Silberschatz, Galvin and Gagne © 2005

Signal Handling n Signals are used in UNIX systems to notify a process that

Signal Handling n Signals are used in UNIX systems to notify a process that a particular event has occurred n A signal handler is used to process signals n 1. Signal is generated by particular event 2. Signal is delivered to a process 3. Signal is handled Options: l Deliver the signal to the thread to which the signal applies l Deliver the signal to every thread in the process l Deliver the signal to certain threads in the process l Assign a specific threa to receive all signals for the process Operating System Concepts 4. 18 Silberschatz, Galvin and Gagne © 2005

Thread Pools n Create a number of threads in a pool where they await

Thread Pools n Create a number of threads in a pool where they await work n Advantages: l Usually slightly faster to service a request with an existing thread than create a new thread l Allows the number of threads in the application(s) to be bound to the size of the pool Operating System Concepts 4. 19 Silberschatz, Galvin and Gagne © 2005

Thread Specific Data n Allows each thread to have its own copy of data

Thread Specific Data n Allows each thread to have its own copy of data n Useful when you do not have control over the thread creation process (i. e. , when using a thread pool) Operating System Concepts 4. 20 Silberschatz, Galvin and Gagne © 2005

Scheduler Activations n Both M: M and Two-level models require communication to maintain the

Scheduler Activations n Both M: M and Two-level models require communication to maintain the appropriate number of kernel threads allocated to the application n Scheduler activations provide upcalls - a communication mechanism from the kernel to the thread library n This communication allows an application to maintain the correct number kernel threads Operating System Concepts 4. 21 Silberschatz, Galvin and Gagne © 2005

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Threads Threads Threads basics A thread is aThreads Threads Threads basics A thread is a
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Threads 1 Processes versus Threads 2 Why ThreadsThreads 1 Processes versus Threads 2 Why Threads
Chapitre X threads Threads o Threads plusieurs activitsChapitre X threads Threads o Threads plusieurs activits
Cours du 312 Threads Threads o threads plusieursCours du 312 Threads Threads o threads plusieurs
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Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads Overview MultithreadingChapter 4 Threads Chapter 4 Threads Overview Multithreading
Chapter 4 Threads Chapter 4 Threads Overview MulticoreChapter 4 Threads Chapter 4 Threads Overview Multicore
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads Overview MultithreadingChapter 4 Threads Chapter 4 Threads Overview Multithreading
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads Overview MultithreadingChapter 4 Threads Chapter 4 Threads Overview Multithreading
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview
Chapter 4 Threads Chapter 4 Threads n OverviewChapter 4 Threads Chapter 4 Threads n Overview