NAME
pthread_attr_init(), pthread_attr_destroy() — initialize or destroy a thread attributes object
SYNOPSIS
#include <pthread.h>
int pthread_attr_init(
pthread_attr_t *attr
);
int pthread_attr_destroy(
pthread_attr_t *attr
);
PARAMETERS
- attr
Pointer to the thread attributes object to be initialized or destroyed.
DESCRIPTION
pthread_attr_init()
initializes a thread attributes object
attr
with the default value for all the thread attributes.
When a thread attributes object is used to create a thread, the values of the
individual attributes determine the characteristics of the new thread.
Attributes objects act like additional parameters to object creation. A single
attributes object can be used in multiple calls to
pthread_create().
After a thread attributes object has been used to initialize one or more
threads, any function affecting the attributes object
does not affect the previously created threads.
The thread attributes and their default values are:
- stacksize
POSIX.1c does not define a default value.
On HP-UX released on PA-RISC platforms, the default is 64K.
On HP-UX released on Itanium(R)-based platforms, the default is 256K.
- guardsize
The default value is
PAGESIZE
bytes.
- stackaddr
The default value is NULL.
- detachstate
The default value is
PTHREAD_CREATE_JOINABLE.
- contentionscope
POSIX.1c does not define a default value.
The default value is set to
PTHREAD_SCOPE_SYSTEM.
The scope can also be specified
externally by using the
options listed in the
pthread_scope_options(5)
manpage.
- inheritsched
POSIX.1c does not define a default value. On HP-UX, the default value is
PTHREAD_INHERIT_SCHED.
- schedpolicy
POSIX.1c does not define a default value. On HP-UX, the default value is
SCHED_TIMESHARE.
- schedparam
POSIX.1c does not define a default value.
- processor
The default value is
PTHREAD_SPUINHERIT_NP.
- binding_type
The default value is
PTHREAD_BIND_ADVISORY_NP.
If an initialized thread attributes object is reinitialized, the
initialization results in undefined behavior.
pthread_attr_destroy()
destroys the thread attributes object
attr.
The destroyed thread attributes object ceases to exist and its resources are
reclaimed. Referencing the object after it has been destroyed results in
undefined behavior.
A destroyed thread attributes object can be reinitialized using thread
attribute initialization routine
pthread_attr_init().
Threads that have already been created using this attributes object are not
affected by the destruction of the thread attributes object.
RETURN VALUE
Upon successful completion,
pthread_attr_init()
and
pthread_attr_destroy()
return zero.
Otherwise, an error number is returned to indicate the error
(the
errno
variable is not set).
ERRORS
If any of the following occur, the
pthread_attr_init()
function returns the corresponding error number:
- [ENOMEM]
There is insufficient memory available in which to initialize the
pthread attributes object.
- [EINVAL]
The value specified by
attr
is invalid.
If any of the following occur, the
pthread_attr_destroy()
function returns the corresponding error number:
- [EINVAL]
The value specified by
attr
is invalid.
AUTHOR
pthread_attr_init()
and
pthread_attr_destroy()
were derived from the IEEE POSIX P1003.1c standard.
STANDARDS CONFORMANCE
pthread_attr_init(): POSIX 1003.1c.
pthread_attr_destroy(): POSIX 1003.1c.
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