pthread






pthread − POSIX.1c Threading API of GNU Pth

GNU Pth 1.2.3 (04‐Feb‐2000)

Application Makefiles:

      #   manually
 CFLAGS=‐I/path/to/pth/include
 LDFLAGS=‐L/path/to/pth/lib
 LIBS=‐lpthread

 #   automatically
 CFLAGS=‘pthread‐config ‐‐cflags‘
 LDFLAGS=‘pthread‐config ‐‐ldflags‘
 LIBS=‘pthread‐config ‐‐libs‘

Application source files:

      #include <pthread.h>




     Overview

     This is the IEEE Std. 1003.1c ("POSIX.1c") conforming threading API of GNU
Portable Threads (Pth). This API is commonly known as ‘‘POSIX threads’’ or in
short ‘‘Pthreads’’. It is provided by Pth with the intention of backward
compatibility to existing multithreaded applications. It is implemented by
mapping the various Pthread API functions to the corresponding Pth API
functions.

     Supported Features

     The following defined feature macros in pthread.h indicate supported
features:

      #define _POSIX_THREADS
 #define _POSIX_THREAD_ATTR_STACKADDR
 #define _POSIX_THREAD_ATTR_STACKSIZE

The following undefined feature macros in pthread.h indicate (still) unsupported
features:

      #undef  _POSIX_THREAD_PRIORITY_SCHEDULING
 #undef  _POSIX_THREAD_PRIO_INHERIT
 #undef  _POSIX_THREAD_PRIO_PROTECT
 #undef  _POSIX_THREAD_PROCESS_SHARED
 #undef  _POSIX_THREAD_SAFE_FUNCTIONS














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     Notes

     A few notes which you should keep in mind when working with the Pth Pthread
API.

Non‐Preemptive Scheduling
    First you have to always remember when working with this Pthread library
    that it uses non‐preemptive scheduling, because it is directly based on Pth
    (Pth for portability reasons is a pure non‐preemptive thread scheduling
    system). So there is no implicit yielding of execution control unless you
    can pthread_* functions which could block and you cannot expect granular
    concurrency in your application, of course.  Nevertheless the responsiveness
    and concurrency of an event driven application is increased greatly because
    of overlapping I/O.

Conflicts with Vendor Implementation
    There can be a conflict between the Pth pthread.h header and a possibly
    existing vendor /usr/include/pthread.h header which was implicitly included
    by some standard vendor headers (like /usr/include/unistd.h). When this
    occurs try to ‘‘#define’’ header‐dependent values which prevent the
    inclusion of the vendor header.

     Further Reading

     First there is a small document included in the Pth source tree, pthread.ps
from Sun Microsystems Inc, which is a very concise summary of the Pthread API.
Use this for a quick reference.

     Then there is ‘‘The Single UNIX Specification, Version 2 − Threads’’, from
The Open Group of 1997 under http://www.opengroup.org/onlinepubs
/007908799/xsh/threads.html.  This is a very complete publically available
description of the Pthread API. Use this when you need details for free.

     Third, you can also buy the official standard from IEEE. It’s IEEE POSIX
1003.1c‐1995 standard (also known as ISO/IEC 9945‐1:1996), which is available as
part of the ANSI/IEEE 1003.1, 1996 edition, standard.

     Finally you can look at the files pthread.c and pthread.h in the Pth source
tree for details of the implementation.

pthread‐config(1), pth(3).



      Ralf S. Engelschall
 rse@engelschall.com
 www.engelschall.com
















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