xref: /netbsd/lib/libpthread/pthread_create.3 (revision 6550d01e)
1.\" $NetBSD: pthread_create.3,v 1.7 2010/07/09 08:51:28 jruoho Exp $
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25.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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55.\" $FreeBSD: src/lib/libpthread/man/pthread_create.3,v 1.16 2002/09/16 19:29:28 mini Exp $
56.\"
57.Dd July 9, 2010
58.Dt PTHREAD_CREATE 3
59.Os
60.Sh NAME
61.Nm pthread_create
62.Nd create a new thread
63.Sh LIBRARY
64.Lb libpthread
65.Sh SYNOPSIS
66.In pthread.h
67.Ft int
68.Fn pthread_create "pthread_t * restrict thread" "const pthread_attr_t * restrict attr" "void *(*start_routine)(void *)" "void * restrict arg"
69.Sh DESCRIPTION
70The
71.Fn pthread_create
72function is used to create a new thread, with attributes specified by
73.Fa attr ,
74within a process.
75If
76.Fa attr
77is
78.Dv NULL ,
79the default attributes are used.
80.Pp
81The attributes specified via
82.Fa attr
83are copied into the new thread.
84Any subsequent modifications to the attributes object
85.Fa attr
86points to will have no effect upon already-created threads.
87It is thus also safe to pass the same
88.Fa attr
89to multiple calls to
90.Fn pthread_create .
91.Pp
92Upon
93successful completion
94.Fn pthread_create
95will store the ID of the created thread in the location specified by
96.Fa thread .
97The thread is created executing
98.Fa start_routine
99with
100.Fa arg
101as its sole argument.
102.Pp
103If the
104.Fa start_routine
105returns, the effect is as if there was an implicit call to
106.Fn pthread_exit
107using the return value of
108.Fa start_routine
109as the exit status.
110Note that the thread in which
111.Fn main
112was originally invoked differs from this.
113When it returns from
114.Fn main ,
115the effect is as if there was an implicit call to
116.Fn exit
117using the return value of
118.Fn main
119as the exit status.
120.Pp
121The signal state of the new thread is initialized as:
122.Bl -bullet -offset indent
123.It
124The signal mask is inherited from the creating thread.
125.It
126The set of signals pending for the new thread is empty.
127.El
128.Sh RETURN VALUES
129If successful,  the
130.Fn pthread_create
131function will return zero.
132Otherwise an error number will be returned to
133indicate the error.
134.Sh ERRORS
135.Fn pthread_create
136shall fail if:
137.Bl -tag -width Er
138.It Bq Er EAGAIN
139The system lacks the necessary resources to create another thread, or
140the system-imposed limit on the total number of threads in a process
141.Dv PTHREAD_THREADS_MAX
142would be exceeded.
143.It Bq Er EINVAL
144The value specified by
145.Fa attr
146is invalid.
147.El
148.Sh SEE ALSO
149.Xr fork 2 ,
150.Xr pthread_attr 3 ,
151.Xr pthread_cleanup_pop 3 ,
152.Xr pthread_cleanup_push 3 ,
153.Xr pthread_exit 3 ,
154.Xr pthread_join 3
155.Sh STANDARDS
156The function conforms to
157.St -p1003.1-2001 .
158