xref: /netbsd-src/lib/libpthread/pthread_create.3 (revision d13ac072348994086a74b5e3aedf51cd0c56a2f4)

.\" $NetBSD: pthread_create.3,v 1.9 2023/04/29 21:37:07 uwe Exp $
.\"
.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
.\" 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.
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.\" 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: src/lib/libpthread/man/pthread_create.3,v 1.16 2002/09/16 19:29:28 mini Exp $
.\"
.Dd July 9, 2010
.Dt PTHREAD_CREATE 3
.Os
.Sh NAME
.Nm pthread_create
.Nd create a new thread
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.
.Ft int
.Fo pthread_create
.Fa "pthread_t * restrict thread"
.Fa "const pthread_attr_t * restrict attr"
.Fa "void *(*start_routine)(void *)"
.Fa "void * restrict arg"
.Fc
.
.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.
.Pp
The attributes specified via
.Fa attr
are copied into the new thread.
Any subsequent modifications to the attributes object
.Fa attr
points to will have no effect upon already-created threads.
It is thus also safe to pass the same
.Fa attr
to multiple calls to
.Fn pthread_create .
.Pp
Upon
successful completion
.Fn pthread_create
will store the ID of the created thread in the location specified by
.Fa thread .
The thread is created executing
.Fa start_routine
with
.Fa arg
as its sole argument.
.Pp
If the
.Fa start_routine
returns, the effect is as if there was an implicit call to
.Xr pthread_exit 3
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
.Xr exit 3
using the return value of
.Fn main
as the exit status.
.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
.Fn pthread_create
shall fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
The system lacks the necessary resources to create another thread, or
the system-imposed limit on the total number of threads in a process
.Dv PTHREAD_THREADS_MAX
would be exceeded.
.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_cleanup_pop 3 ,
.Xr pthread_cleanup_push 3 ,
.Xr pthread_exit 3 ,
.Xr pthread_join 3
.Sh STANDARDS
The function conforms to
.St -p1003.1-2001 .