1. Chapter 5: Threads Overview Multithreading Models（多线程模型）
Threading Issues
Pthreads
Solaris 2 Threads
Windows 2000 Threads
Linux Threads
Java Threads
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2. Thread
A thread, sometimes called a lightweight process(LWP), is a basic unit of CPU utilization; it comprises a thread ID, a program counter, a register set , and a stack.
A traditional (or heavyweight) process has a single thread of control or multiple threads of control.
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3. Single and Multithreaded Processes
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4. Benefits Responsiveness （相应度高） Resource Sharing Economy
Utilization of MP Architectures
（多处理器体系结构的利用）
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5. User Threads Thread management done by user-level threads library
Examples
- POSIX Pthreads
- Mach C-threads
- Solaris threads
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6. Kernel Threads Supported by the Kernel Examples
- Windows 95/98/NT/2000
- Solaris
- Tru64 UNIX
- BeOS
- Linux
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7. Multithreading Models
Many-to-One
One-to-One
Many-to-Many
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8. Many-to-One Many user-level threads mapped to single kernel thread.
The entire process will block if a thread makes a blocking system call.
Multiple threads are unble to run in parallel on multiprocessors.
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9. Many-to-One Model
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10. One-to-One Each user-level thread maps to kernel thread.
Most implementations of this model restrict the number of threads supported by the system.
Examples
- Windows 95/98/NT/2000
- OS/2
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11. One-to-one Model
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12. 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
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13. Many-to-Many Model
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14. 5 Threading Issues Semantics of fork() and exec() system calls.
Thread cancellation.
Signal handling
Thread specific data
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15. Pthreads
a POSIX standard (IEEE c) API for thread creation and synchronization.
API specifies behavior of the thread library, not an implementation. Implementation is up to development of the library.
Common in UNIX operating systems.
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16. Solaris 2 Threads
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17. Solaris Process
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18. 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
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19. 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)
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20. Java Threads Java threads may be created by: Extending Thread class
Implementing the Runnable interface
Java threads are managed by the JVM.
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21. Java Thread States
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22. Summary Overview Multithreading Models（多线程模型） Threading Issues
Five threads
Pthreads
Solaris 2 Threads
Windows 2000 Threads
Linux Threads
Java Threads
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