pthread.3

Linux下的中文输入法

Inclusion of the \fI<pthread.h\fR> header will make visible symbols defined
in the headers \fI<sched.h\fR> and \fI<time.h\fR>.
.SH "APPLICATION USAGE"
.IX Header "APPLICATION USAGE"
An interpretation request has been filed with \s-1IEEE\s0 \s-1PASC\s0 concerning
requirements for visibility of symbols in this header.
.SH "FUTURE DIRECTIONS"
.IX Header "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fI\fIpthread_attr_init()\fI\fR,
\&\fI\fIpthread_attr_getguardsize()\fI\fR,
\&\fI\fIpthread_attr_setscope()\fI\fR,
\&\fI\fIpthread_cancel()\fI\fR,
\&\fI\fIpthread_cleanup_push()\fI\fR,
\&\fI\fIpthread_cond_init()\fI\fR,
\&\fI\fIpthread_cond_signal()\fI\fR,
\&\fI\fIpthread_cond_wait()\fI\fR,
\&\fI\fIpthread_condattr_init()\fI\fR,
\&\fI\fIpthread_create()\fI\fR,
\&\fI\fIpthread_detach()\fI\fR,
\&\fI\fIpthread_equal()\fI\fR,
\&\fI\fIpthread_exit()\fI\fR,
\&\fI\fIpthread_getconcurrency()\fI\fR,
\&\fI\fIpthread_getschedparam()\fI\fR,
\&\fI\fIpthread_join()\fI\fR,
\&\fI\fIpthread_key_create()\fI\fR,
\&\fI\fIpthread_key_delete()\fI\fR,
\&\fI\fIpthread_mutex_init()\fI\fR,
\&\fI\fIpthread_mutex_lock()\fI\fR,
\&\fI\fIpthread_mutex_setprioceiling()\fI\fR,
\&\fI\fIpthread_mutexattr_init()\fI\fR,
\&\fI\fIpthread_mutexattr_gettype()\fI\fR,
\&\fI\fIpthread_mutexattr_setprotocol()\fI\fR,
\&\fI\fIpthread_once()\fI\fR,
\&\fI\fIpthread_self()\fI\fR,
\&\fI\fIpthread_setcancelstate()\fI\fR,
\&\fI\fIpthread_setspecific()\fI\fR,
\&\fI\fIpthread_rwlock_init()\fI\fR,
\&\fI\fIpthread_rwlock_rdlock()\fI\fR,
\&\fI\fIpthread_rwlock_unlock()\fI\fR,
\&\fI\fIpthread_rwlock_wrlock()\fI\fR,
\&\fI\fIpthread_rwlockattr_init()\fI\fR,
\&\fI<sched.h\fR>,
\&\fI<time.h\fR>.
.SH "_\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|_"
.IX Header "______________________________________________________________________"
.SH "NAME"
\&\fBpthread_atfork\fR \- register fork handlers
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
#include <sys/types.h>
.PP
#include <unistd.h>
.PP
int pthread_atfork(void (*\fIprepare\fR)(void), void (*\fIparent\fR)(void),
void (*\fIchild\fR)(void));
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fI\fIpthread_atfork()\fI\fR function declares fork handlers to be called
before and after \fI\fIfork()\fI\fR, in the context of the thread that called
\&\fI\fIfork()\fI\fR. The \fIprepare\fR fork handler is called before \fI\fIfork()\fI\fR
processing commences. The \fIparent\fR fork handle is called after
\&\fI\fIfork()\fI\fR processing completes in the parent process. The \fIchild\fR fork
handler is called after \fI\fIfork()\fI\fR processing completes in the child
process. If no handling is desired at one or more of these three points,
the corresponding fork handler address(es) may be set to \s-1NULL\s0.
.PP
The order of calls to \fI\fIpthread_atfork()\fI\fR is significant. The \fIparent\fR
and \fIchild\fR fork handlers are called in the order in which they were
established by calls to \fI\fIpthread_atfork()\fI\fR. The \fIprepare\fR fork
handlers are called in the opposite order.
.SH "RETURN VALUE"
.IX Header "RETURN VALUE"
Upon successful completion, \fI\fIpthread_atfork()\fI\fR returns a value of zero.
Otherwise, an error number is returned to indicate the error.
.SH "ERRORS"
.IX Header "ERRORS"
The \fI\fIpthread_atfork()\fI\fR function will fail if:
.IP "[\s-1ENOMEM\s0]" 4
.IX Item "[ENOMEM]"
Insufficient table space exists to record the fork handler addresses.
.PP
The \fI\fIpthread_atfork()\fI\fR function will not return an error code of
[\s-1EINTR\s0].
.SH "EXAMPLES"
.IX Header "EXAMPLES"
None.
.SH "APPLICATION USAGE"
.IX Header "APPLICATION USAGE"
None.
.SH "FUTURE DIRECTIONS"
.IX Header "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fI\fIatexit()\fI\fR,
\&\fI\fIfork()\fI\fR,
\&\fI<sys/types.h\fR>
.SH "_\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|_"
.IX Header "______________________________________________________________________"
.SH "NAME"
\&\fBpthread_attr_init,\fR \fBpthread_attr_destroy\fR
\&\- initialise and destroy threads attribute object
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
#include <pthread.h>
.PP
int pthread_attr_init(pthread_attr_t *\fIattr\fR);
.PP
int pthread_attr_destroy(pthread_attr_t *\fIattr\fR);
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The function \fI\fIpthread_attr_init()\fI\fR initialises a thread attributes
object \fIattr\fR with the default value for all of the individual
attributes used by a given implementation.
.PP
The resulting attribute object (possibly modified by setting individual
attribute values), when used by \fI\fIpthread_create()\fI\fR, defines the
attributes of the thread created. A single attributes object can be used
in multiple simultaneous calls to \fI\fIpthread_create()\fI\fR.
.PP
The \fI\fIpthread_attr_destroy()\fI\fR function is used to destroy a thread
attributes object. An implementation may cause \fI\fIpthread_attr_destroy()\fI\fR
to set \fIattr\fR to an implementation-dependent invalid value. The
behaviour of using the attribute after it has been destroyed is
undefined.
.SH "RETURN VALUE"
.IX Header "RETURN VALUE"
Upon successful completion, \fI\fIpthread_attr_init()\fI\fR and
\&\fI\fIpthread_attr_destroy()\fI\fR return a value of 0. Otherwise, an error
number is returned to indicate the error.
.SH "ERRORS"
.IX Header "ERRORS"
The \fI\fIpthread_attr_init()\fI\fR function will fail if:
.IP "[\s-1ENOMEM\s0]" 4
.IX Item "[ENOMEM]"
Insufficient memory exists to initialise the thread attributes object.
.PP
These functions will not return an error code of [\s-1EINTR\s0].
.SH "EXAMPLES"
.IX Header "EXAMPLES"
None.
.SH "APPLICATION USAGE"
.IX Header "APPLICATION USAGE"
None.
.SH "FUTURE DIRECTIONS"
.IX Header "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fI\fIpthread_attr_setstackaddr()\fI\fR,
\&\fI\fIpthread_attr_setstacksize()\fI\fR,
\&\fI\fIpthread_attr_setdetachstate()\fI\fR,
\&\fI\fIpthread_create()\fI\fR,
\&\fI<pthread.h\fR>.
.SH "_\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|_"
.IX Header "______________________________________________________________________"
.SH "NAME"
\&\fBpthread_attr_setdetachstate,\fR \fBpthread_attr_getdetachstate\fR
\&\- set and get detachstate attribute
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
#include <pthread.h>
.PP
int pthread_attr_setdetachstate(pthread_attr_t *\fIattr\fR, int \fIdetachstate\fR);
.PP
int pthread_attr_getdetachstate(const pthread_attr_t *\fIattr\fR, int *\fIdetachstate\fR);
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fIdetachstate\fR attribute controls whether the thread is created in a
detached state. If the thread is created detached, then use of the \s-1ID\s0 of
the newly created thread by the \fI\fIpthread_detach()\fI\fR or \fI\fIpthread_join()\fI\fR
function is an error.
.PP
The \fI\fIpthread_attr_setdetachstate()\fI\fR and
\&\fI\fIpthread_attr_getdetachstate()\fI\fR, respectively, set and get the
\&\fIdetachstate\fR attribute in the \fIattr\fR object.
.PP
The \fIdetachstate\fR can be set to either \s-1PTHREAD_CREATE_DETACHED\s0 or
\&\s-1PTHREAD_CREATE_JOINABLE\s0. A value of \s-1PTHREAD_CREATE_DETACHED\s0 causes
all threads created with \fIattr\fR to be in the detached state, whereas
using a value of \s-1PTHREAD_CREATE_JOINABLE\s0 causes all threads created
with \fIattr\fR to be in the joinable state. The default value of the
\&\fIdetachstate\fR attribute is \s-1PTHREAD_CREATE_JOINABLE\s0 .
.SH "RETURN VALUE"
.IX Header "RETURN VALUE"
Upon successful completion, \fI\fIpthread_attr_setdetachstate()\fI\fR and
\&\fI\fIpthread_attr_getdetachstate()\fI\fR return a value of 0. Otherwise, an
error number is returned to indicate the error.
.PP
The \fI\fIpthread_attr_getdetachstate()\fI\fR function stores the value of the
\&\fIdetachstate\fR attribute in \fIdetachstate\fR if successful.
.SH "ERRORS"
.IX Header "ERRORS"
The \fI\fIpthread_attr_setdetachstate()\fI\fR function will fail if:
.IP "[\s-1EINVAL\s0]" 4
.IX Item "[EINVAL]"
The value of \fIdetachstate\fR was not valid
.PP
These functions will not return an error code of [\s-1EINTR\s0].
.SH "EXAMPLES"
.IX Header "EXAMPLES"
None.
.SH "APPLICATION USAGE"
.IX Header "APPLICATION USAGE"
None.
.SH "FUTURE DIRECTIONS"
.IX Header "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fI\fIpthread_attr_init()\fI\fR,
\&\fI\fIpthread_attr_setstackaddr()\fI\fR,
\&\fI\fIpthread_attr_setstacksize()\fI\fR,
\&\fI\fIpthread_create()\fI\fR,
\&\fI<pthread.h\fR>.
.SH "_\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|_"
.IX Header "______________________________________________________________________"
.SH "NAME"
\&\fBpthread_attr_getguardsize,\fR \fBpthread_attr_setguardsize\fR \-
get or set the thread guardsize attribute
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
#include <pthread.h>
.PP
int pthread_attr_getguardsize(const pthread_attr_t \fI*attr\fR, size_t
\&\fI*guardsize\fR); int pthread_attr_setguardsize(pthread_attr_t \fI*attr\fR,
size_t \fIguardsize\fR);
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fIguardsize\fR attribute controls the size of the guard area for the
created thread's stack. The \fIguardsize\fR attribute provides protection
against overflow of the stack pointer. If a thread's stack is created
with guard protection, the implementation allocates extra memory at the
overflow end of the stack as a buffer against stack overflow of the
stack pointer. If an application overflows into this buffer an error
results (possibly in a \s-1SIGSEGV\s0 signal being delivered to the thread).
.PP
The \fIguardsize\fR attribute is provided to the application
for two reasons:
.IP "1." 4
Overflow protection can potentially result in wasted system resources.
An application that creates a large number of threads, and which knows
its threads will never overflow their stack, can save system resources
by turning off guard areas.
.IP "2." 4
When threads allocate large data structures on the stack,
large guard areas may be needed to detect stack overflow.
.PP
The \fI\fIpthread_attr_getguardsize()\fI\fR function gets the \fIguardsize\fR
attribute in the \fIattr\fR object. This attribute is returned in the
\&\fIguardsize\fR parameter.
.PP
The \fI\fIpthread_attr_setguardsize()\fI\fR function sets the \fIguardsize\fR
attribute in the \fIattr\fR object. The new value of this attribute is
obtained from the \fIguardsize\fR parameter. If \fIguardsize\fR is zero,
a guard area will not be provided for threads created with \fIattr\fR.
If \fIguardsize\fR is greater than zero, a guard area of at least size
\&\fIguardsize\fR bytes is provided for each thread created with \fIattr\fR.
.PP
A conforming implementation is permitted to round up the value
contained in \fIguardsize\fR to a multiple of the configurable system
variable \s-1PAGESIZE\s0 (see \fI<sys/mman.h\fR>). If an implementation rounds
up the value of \fIguardsize\fR to a multiple of \s-1PAGESIZE\s0, a call to
\&\fI\fIpthread_attr_getguardsize()\fI\fR specifying \fIattr\fR will store in the
\&\fIguardsize\fR parameter the guard size specified by the previous
\&\fI\fIpthread_attr_setguardsize()\fI\fR function call.
.PP
The default value of the \fIguardsize\fR attribute is \s-1PAGESIZE\s0 bytes. The
actual value of \s-1PAGESIZE\s0 is implementation-dependent and may not be the
same on all implementations.
.PP
If the \fIstackaddr\fR attribute has been set (that is, the caller is
allocating and managing its own thread stacks), the \fIguardsize\fR
attribute is ignored and no protection will be provided by the
implementation. It is the responsibility of the application to manage
stack overflow along with stack allocation and management in this case.
.SH "RETURN VALUE"
.IX Header "RETURN VALUE"
If successful, the \fI\fIpthread_attr_getguardsize()\fI\fR and
\&\fI\fIpthread_attr_setguardsize()\fI\fR functions return zero. Otherwise, an
error number is returned to indicate the error.
.SH "ERRORS"
.IX Header "ERRORS"
The \fI\fIpthread_attr_getguardsize()\fI\fR and \fI\fIpthread_attr_setguardsize()\fI\fR
functions will fail if:
.IP "[\s-1EINVAL\s0]" 4
.IX Item "[EINVAL]"
The attribute \fIattr\fR is invalid.
.IP "[\s-1EINVAL\s0]" 4
.IX Item "[EINVAL]"
The parameter \fIguardsize\fR is invalid.
.IP "[\s-1EINVAL\s0]" 4
.IX Item "[EINVAL]"
The parameter \fIguardsize\fR contains an invalid value.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
None.
.SH "APPLICATION USAGE"
.IX Header "APPLICATION USAGE"
None.
.SH "FUTURE DIRECTIONS"
.IX Header "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fI<pthread.h\fR>.
.SH "_\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|__\|_"
.IX Header "______________________________________________________________________"
.SH "NAME"
\&\fBpthread_attr_setinheritsched,\fR \fBpthread_attr_getinheritsched\fR
\&\- set and get inheritsched attribute
(\fBREALTIME THREADS\fR)
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
#include <pthread.h>
.PP
int pthread_attr_setinheritsched(pthread_attr_t *\fIattr\fR,
int \fIinheritsched\fR);
int pthread_attr_getinheritsched(const pthread_attr_t *\fIattr\fR,
int *\fIinheritsched\fR);
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The functions \fI\fIpthread_attr_setinheritsched()\fI\fR and
\&\fI\fIpthread_attr_getinheritsched()\fI\fR, respectively, set and get the
\&\fIinheritsched\fR attribute in the \fIattr\fR argument.
.PP
When the attribute objects are used by \fI\fIpthread_create()\fI\fR, the
\&\fIinheritsched\fR attribute determines how the other scheduling attributes
of the created thread are to be set:
.IP "\s-1PTHREAD_INHERIT_SCHED\s0" 4
.IX Item "PTHREAD_INHERIT_SCHED"
Specifies that the scheduling policy and associated attributes are to
be inherited from the creating thread, and the scheduling attributes in
this \fIattr\fR argument are to be ignored.
.IP "\s-1PTHREAD_EXPLICIT_SCHED\s0" 4
.IX Item "PTHREAD_EXPLICIT_SCHED"
Specifies that the scheduling policy and associated attributes
are to be set to the corresponding values from this attribute object.
.PP
The symbols \s-1PTHREAD_INHERIT_SCHED\s0 and \s-1PTHREAD_EXPLICIT_SCHED\s0 are defined
in the header \fI<pthread.h\fR>.
.SH "RETURN VALUE"
.IX Header "RETURN VALUE"
If successful, the \fI\fIpthread_attr_setinheritsched()\fI\fR and
\&\fI\fIpthread_attr_getinheritsched()\fI\fR functions return zero. Otherwise, an
error number is returned to indicate the error.
.SH "ERRORS"
.IX Header "ERRORS"
The \fI\fIpthread_attr_setinheritsched()\fI\fR and
\&\fI\fIpthread_attr_getinheritsched()\fI\fR functions will fail if:
.IP "[\s-1ENOSYS\s0]" 4
.IX Item "[ENOSYS]"
The option _POSIX_THREAD_PRIORITY_SCHEDULING is not defined and the
implementation does not support the function.
.PP
The \fI\fIpthread_attr_setinheritsched()\fI\fR function may fail if:
.IP "[\s-1EINVAL\s0]" 4
.IX Item "[EINVAL]"
The value of the attribute being set is not valid.
.IP "[\s-1ENOTSUP\s0]" 4
.IX Item "[ENOTSUP]"
An attempt was made to set the attribute to an unsupported value.
.SH "EXAMPLES"
.IX Header "EXAMPLES"