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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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pthread_attr_setscope(3) Library Functions Manualpthread_attr_setscope(3)
pthread_attr_setscope, pthread_attr_getscope - set/get contention
scope attribute in thread attributes object
POSIX threads library (libpthread, -lpthread)
#include <pthread.h>
int pthread_attr_setscope(pthread_attr_t *attr, int scope);
int pthread_attr_getscope(const pthread_attr_t *restrict attr,
int *restrict scope);
The pthread_attr_setscope() function sets the contention scope
attribute of the thread attributes object referred to by attr to
the value specified in scope. The contention scope attribute
defines the set of threads against which a thread competes for
resources such as the CPU. POSIX.1 specifies two possible values
for scope:
PTHREAD_SCOPE_SYSTEM
The thread competes for resources with all other threads in
all processes on the system that are in the same scheduling
allocation domain (a group of one or more processors).
PTHREAD_SCOPE_SYSTEM threads are scheduled relative to one
another according to their scheduling policy and priority.
PTHREAD_SCOPE_PROCESS
The thread competes for resources with all other threads in
the same process that were also created with the
PTHREAD_SCOPE_PROCESS contention scope.
PTHREAD_SCOPE_PROCESS threads are scheduled relative to
other threads in the process according to their scheduling
policy and priority. POSIX.1 leaves it unspecified how
these threads contend with other threads in other process
on the system or with other threads in the same process
that were created with the PTHREAD_SCOPE_SYSTEM contention
scope.
POSIX.1 requires that an implementation support at least one of
these contention scopes. Linux supports PTHREAD_SCOPE_SYSTEM, but
not PTHREAD_SCOPE_PROCESS.
On systems that support multiple contention scopes, then, in order
for the parameter setting made by pthread_attr_setscope() to have
effect when calling pthread_create(3), the caller must use
pthread_attr_setinheritsched(3) to set the inherit-scheduler
attribute of the attributes object attr to PTHREAD_EXPLICIT_SCHED.
The pthread_attr_getscope() function returns the contention scope
attribute of the thread attributes object referred to by attr in
the buffer pointed to by scope.
On success, these functions return 0; on error, they return a
nonzero error number.
pthread_attr_setscope() can fail with the following errors:
EINVAL An invalid value was specified in scope.
ENOTSUP
scope specified the value PTHREAD_SCOPE_PROCESS, which is
not supported on Linux.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ pthread_attr_setscope(), │ Thread safety │ MT-Safe │
│ pthread_attr_getscope() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
POSIX.1-2001.
The PTHREAD_SCOPE_SYSTEM contention scope typically indicates that
a user-space thread is bound directly to a single kernel-
scheduling entity. This is the case on Linux for the obsolete
LinuxThreads implementation and the modern NPTL implementation,
which are both 1:1 threading implementations.
POSIX.1 specifies that the default contention scope is
implementation-defined.
pthread_attr_init(3), pthread_attr_setaffinity_np(3),
pthread_attr_setinheritsched(3), pthread_attr_setschedparam(3),
pthread_attr_setschedpolicy(3), pthread_create(3), pthreads(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 pthread_attr_setscope(3)
Pages that refer to this page: pthread_attr_init(3), pthread_attr_setinheritsched(3), pthread_getattr_default_np(3), pthread_getattr_np(3), pthread_setconcurrency(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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