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Chapter 5: Threads

Chapter 5: Threads. Overview Multithreading Models Threading Issues Pthreads Solaris 2 Threads Windows 2000 Threads Linux Threads Java Threads. Example: fork(). main() { int pid = 0; printf(“the parent is going to fork<br>”); if (pid = fork() != 0)

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Chapter 5: Threads

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  1. Chapter 5: Threads • Overview • Multithreading Models • Threading Issues • Pthreads • Solaris 2 Threads • Windows 2000 Threads • Linux Threads • Java Threads Operating System Concepts

  2. Example: fork() main() { int pid = 0; printf(“the parent is going to fork\n”); if (pid = fork() != 0) printf(“I am the father of %d\n”, pid); else printf(“I am the child\n”); } Operating System Concepts

  3. Single and Multithreaded Processes Operating System Concepts

  4. Benefits • Responsiveness (e.g. thread as GUI engine) • Resource Sharing (e.g. shared variable) • Economy (e.g. save memory) • Utilization of MP Architectures Operating System Concepts

  5. User Threads • Thread management done by user-levelthreads library • Examples - POSIX Pthreads - Mach C-threads - Solaris threads Operating System Concepts

  6. Example: Solaris 2 Operating System Concepts

  7. Example: Solaris 2 User-level thread kernel thread CPU Operating System Concepts

  8. Kernel Threads • Supported by the Kernel • Examples - Windows 95/98/NT/2000 - Solaris 2 Operating System Concepts

  9. Multithreading Models • Many-to-One • One-to-One • Many-to-Many Operating System Concepts

  10. Many-to-One • Many user-level threads mapped to single kernel thread. • Used on systems that do not support kernel threads. Operating System Concepts

  11. Many-to-One Model Operating System Concepts

  12. One-to-One • Each user-level thread maps to kernel thread. • Examples - Windows 95/98/NT/2000 - OS/2 Operating System Concepts

  13. One-to-one Model Operating System Concepts

  14. Many-to-Many Model • Allows many user level threads to be mapped to many kernel threads. • Allows the operating system to create a sufficient number of kernel threads. • Solaris 2 • Windows NT/2000 with the ThreadFiber package Operating System Concepts

  15. Many-to-Many Model Operating System Concepts

  16. Threading Issues • Semantics of fork() system call duplicate all threads or one • Semantics of exec() system call replace the entire process codes • Thread cancellation cancellation point • Signal handling • Thread pools • Thread specific data Operating System Concepts

  17. Pthreads • a POSIX standard (IEEE 1003.1c) API for thread creation and synchronization. • API specifies behavior of the thread library, implementation is up to development of the library. • Common in UNIX operating systems. Operating System Concepts

  18. Solaris 2 Threads Operating System Concepts

  19. Solaris Process Operating System Concepts

  20. Windows 2000 Threads • Implements the one-to-one mapping. • Each thread contains - a thread id - register set - separate user and kernel stacks - private data storage area Operating System Concepts

  21. Linux Threads • Linux refers to them as tasks rather than threads. • Thread creation is done through clone() system call. • Clone() allows a child task to share the address space of the parent task (process) Operating System Concepts

  22. Java Threads • Java threads may be created by: • Extending Thread class • Implementing the Runnable interface • Java threads are managed by the JVM. Operating System Concepts

  23. Java Thread States Operating System Concepts

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