pthread_attr_getscope(3)pthread_attr_getscope(3)NAMEpthread_attr_getscope - Obtains the contention scope attribute of the
specified thread attributes object
SYNOPSIS
#include <pthread.h>
int pthread_attr_getscope(
const pthread_attr_t *attr,
int *scope );
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program Interface
PARAMETERS
Address of the thread attributes object whose contention scope
attribute is obtained. Receives the value of the contention scope
attribute of the thread attributes object specified by attr.
DESCRIPTION
This routine obtains the value of the contention scope attribute of the
thread attributes object specified in the attr argument and stores it
in the location specified by the scope argument. The specified
attributes object must already be initialized at the time this routine
is called.
The contention scope attribute specifies the set of threads with which
a thread must compete for processing resources. The contention scope
attribute specifies whether the new thread competes for processing
resources only with other threads in its own process, called process
contention scope, or with all threads on the system, called system con‐
tention scope.
DECthreads selects at most one thread to execute on each processor at
any point in time. DECthreads resolves the contention based on each
thread's scheduling attributes (for example, priority) and scheduling
policy (for example, round-robin).
A thread created using a thread attributes object whose contention
scope attribute is set to PTHREAD_SCOPE_PROCESS contends for processing
resources with other threads within its own process that also were cre‐
ated with PTHREAD_SCOPE_PROCESS. It is unspecified how such threads
are scheduled relative to threads in other processes or threads in the
same process that were created with PTHREAD_SCOPE_SYSTEM contention
scope.
A thread created using a thread attributes object whose contention
scope attribute is set to PTHREAD_SCOPE_SYSTEM contends for processing
resources with other threads in any process that also were created with
PTHREAD_SCOPE_SYSTEM.
NOTES
The value of the contention scope attribute of a particular thread
attributes object does not necessarily correspond to the actual sched‐
uling contention scope of any existing thread in your multithreaded
program.
RETURN VALUES
If an error condition occurs, this routine returns an integer value
indicating the type of error. Possible return values are as follows:
Successful completion. The value specified by attr is not a valid
thread attributes object. This routine is not supported by the imple‐
mentation.
ERRORS
None
SEE ALSO
Functions: pthread_attr_init(3), pthread_attr_setscope(3)
Manuals: Guide to DECthreads and Programmer's Guide
pthread_attr_getscope(3)