[apple/libpthread.git] / man / pthread_create.3

.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by John Birrell.
.\" 4. Neither the name of the author nor the names of any co-contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd March 15, 2014
.Dt PTHREAD_CREATE 3
.Os
.Sh NAME
.Nm pthread_create
.Nd create a new thread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_create "pthread_t *thread" "const pthread_attr_t *attr" "void *(*start_routine)(void *)" "void *arg"
.Sh DESCRIPTION
The
.Fn pthread_create
function is used to create a new thread, with attributes specified by
.Fa attr ,
within a process.
If
.Fa attr
is
.Dv NULL ,
the default attributes are used.
If the attributes specified by
.Fa attr
are modified later, the thread's attributes are not affected.
Upon
successful completion
.Fn pthread_create
will store the ID of the created thread in the location specified by
.Fa thread .
.Pp
The thread is created executing
.Fa start_routine
with
.Fa arg
as its sole argument.
If the
.Fa start_routine
returns, the effect is as if there was an implicit call to
.Fn pthread_exit
using the return value of
.Fa start_routine
as the exit status.
Note that the thread in which
.Fn main
was originally invoked differs from this.
When it returns from
.Fn main ,
the effect is as if there was an implicit call to
.Fn exit
using the return value of
.Fn main
as the exit status.
.Pp
Upon thread exit the storage for the thread must be reclaimed by another
thread via a call to
.Fn pthread_join .
Alternatively,
.Fn pthread_detach
may be called on the thread to indicate that the system may automatically
reclaim the thread storage upon exit.
The
.Fn pthread_attr_setdetachstate
function may be used on the
.Fa attr
argument passed to
.Fn pthread_create
in order to achieve the same effect as a call to
.Fn pthread_detach
on the newly created thread.
.Pp
The signal state of the new thread is initialized as:
.Bl -bullet -offset indent
.It
The signal mask is inherited from the creating thread.
.It
The set of signals pending for the new thread is empty.
.El
.Sh RETURN VALUES
If successful, the
.Fn pthread_create
function will return zero.
Otherwise an error number will be returned to
indicate the error.
.Sh ERRORS
The
.Fn pthread_create
function will fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
The system lacked the necessary resources to create another thread, or
the system-imposed limit on the total number of threads in a process
[PTHREAD_THREADS_MAX] would be exceeded.
.It Bq Er EPERM
The caller does not have appropriate permission to set the required scheduling
parameters or scheduling policy.
.It Bq Er EINVAL
The value specified by
.Fa attr
is invalid.
.El
.Sh SEE ALSO
.Xr fork 2 ,
.Xr pthread_attr 3 ,
.Xr pthread_cancel 3 ,
.Xr pthread_cleanup_pop 3 ,
.Xr pthread_cleanup_push 3 ,
.Xr pthread_exit 3 ,
.Xr pthread_join 3
.Sh STANDARDS
The
.Fn pthread_create
function conforms to
.St -p1003.1-96 .
Commit	Line	Data
f1a1da6c A	1	.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by John Birrell.
	15	.\" 4. Neither the name of the author nor the names of any co-contributors
	16	.\" may be used to endorse or promote products derived from this software
	17	.\" without specific prior written permission.
	18	.\"
	19	.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
	20	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	21	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	22	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	23	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	24	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	25	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	26	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	27	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	28	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	29	.\" SUCH DAMAGE.
	30	.\"
2546420a	31	.\" $FreeBSD$
f1a1da6c	32	.\"
2546420a	33	.Dd March 15, 2014
f1a1da6c A	34	.Dt PTHREAD_CREATE 3
	35	.Os
	36	.Sh NAME
	37	.Nm pthread_create
	38	.Nd create a new thread
	39	.Sh SYNOPSIS
2546420a	40	.In pthread.h
f1a1da6c	41	.Ft int
2546420a	42	.Fn pthread_create "pthread_t thread" "const pthread_attr_t attr" "void (start_routine)(void )" "void arg"
f1a1da6c A	43	.Sh DESCRIPTION
	44	The
	45	.Fn pthread_create
	46	function is used to create a new thread, with attributes specified by
	47	.Fa attr ,
	48	within a process.
	49	If
	50	.Fa attr
2546420a A	51	is
	52	.Dv NULL ,
	53	the default attributes are used.
f1a1da6c A	54	If the attributes specified by
	55	.Fa attr
	56	are modified later, the thread's attributes are not affected.
2546420a A	57	Upon
2546420a A	58	successful completion
f1a1da6c A	59	.Fn pthread_create
	60	will store the ID of the created thread in the location specified by
	61	.Fa thread .
	62	.Pp
2546420a A	63	The thread is created executing
2546420a A	64	.Fa start_routine
f1a1da6c A	65	with
	66	.Fa arg
	67	as its sole argument.
2546420a	68	If the
f1a1da6c A	69	.Fa start_routine
f1a1da6c A	70	returns, the effect is as if there was an implicit call to
2546420a	71	.Fn pthread_exit
f1a1da6c A	72	using the return value of
	73	.Fa start_routine
	74	as the exit status.
	75	Note that the thread in which
	76	.Fn main
	77	was originally invoked differs from this.
	78	When it returns from
	79	.Fn main ,
	80	the effect is as if there was an implicit call to
2546420a	81	.Fn exit
f1a1da6c A	82	using the return value of
	83	.Fn main
	84	as the exit status.
	85	.Pp
	86	Upon thread exit the storage for the thread must be reclaimed by another
	87	thread via a call to
	88	.Fn pthread_join .
	89	Alternatively,
	90	.Fn pthread_detach
	91	may be called on the thread to indicate that the system may automatically
	92	reclaim the thread storage upon exit.
	93	The
	94	.Fn pthread_attr_setdetachstate
	95	function may be used on the
	96	.Fa attr
	97	argument passed to
	98	.Fn pthread_create
	99	in order to achieve the same effect as a call to
	100	.Fn pthread_detach
	101	on the newly created thread.
	102	.Pp
	103	The signal state of the new thread is initialized as:
	104	.Bl -bullet -offset indent
	105	.It
	106	The signal mask is inherited from the creating thread.
	107	.It
	108	The set of signals pending for the new thread is empty.
	109	.El
	110	.Sh RETURN VALUES
2546420a	111	If successful, the
f1a1da6c A	112	.Fn pthread_create
f1a1da6c A	113	function will return zero.
2546420a	114	Otherwise an error number will be returned to
f1a1da6c A	115	indicate the error.
f1a1da6c A	116	.Sh ERRORS
2546420a	117	The
f1a1da6c	118	.Fn pthread_create
2546420a	119	function will fail if:
f1a1da6c A	120	.Bl -tag -width Er
	121	.It Bq Er EAGAIN
	122	The system lacked the necessary resources to create another thread, or
	123	the system-imposed limit on the total number of threads in a process
	124	[PTHREAD_THREADS_MAX] would be exceeded.
2546420a A	125	.It Bq Er EPERM
	126	The caller does not have appropriate permission to set the required scheduling
	127	parameters or scheduling policy.
f1a1da6c A	128	.It Bq Er EINVAL
	129	The value specified by
	130	.Fa attr
	131	is invalid.
	132	.El
	133	.Sh SEE ALSO
	134	.Xr fork 2 ,
2546420a A	135	.Xr pthread_attr 3 ,
2546420a A	136	.Xr pthread_cancel 3 ,
f1a1da6c A	137	.Xr pthread_cleanup_pop 3 ,
f1a1da6c A	138	.Xr pthread_cleanup_push 3 ,
f1a1da6c A	139	.Xr pthread_exit 3 ,
	140	.Xr pthread_join 3
	141	.Sh STANDARDS
2546420a	142	The
f1a1da6c	143	.Fn pthread_create
2546420a	144	function conforms to
f1a1da6c	145	.St -p1003.1-96 .