man/pthread_create.3

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  33 .Dd April 4, 1996
  34 .Dt PTHREAD_CREATE 3
  35 .Os
  36 .Sh NAME
  37 .Nm pthread_create
  38 .Nd create a new thread
  39 .Sh SYNOPSIS
  40 .Fd #include <pthread.h>
  41 .Ft int
  42 .Fo pthread_create
  43 .Fa "pthread_t *restrict thread"
  44 .Fa "const pthread_attr_t *restrict attr"
  45 .Fa "void *(*start_routine)(void *)"
  46 .Fa "void *restrict arg"
  47 .Fc
  48 .Sh DESCRIPTION
  49 The
  50 .Fn pthread_create
  51 function is used to create a new thread, with attributes specified by
  52 .Fa attr ,
  53 within a process.
  54 If
  55 .Fa attr
  56 is NULL, the default attributes are used.
  57 If the attributes specified by
  58 .Fa attr
  59 are modified later, the thread's attributes are not affected.
  60 Upon successful completion,
  61 .Fn pthread_create
  62 will store the ID of the created thread in the location specified by
  63 .Fa thread .
  64 .Pp
  65 Upon its creation, the thread executes
  66 .Fa start_routine ,
  67 with
  68 .Fa arg
  69 as its sole argument.
  70 If
  71 .Fa start_routine
  72 returns, the effect is as if there was an implicit call to
  73 .Fn pthread_exit ,
  74 using the return value of
  75 .Fa start_routine
  76 as the exit status.
  77 Note that the thread in which
  78 .Fn main
  79 was originally invoked differs from this.
  80 When it returns from
  81 .Fn main ,
  82 the effect is as if there was an implicit call to
  83 .Fn exit ,
  84 using the return value of
  85 .Fn main
  86 as the exit status.
  87 .Pp
  88 Upon thread exit the storage for the thread must be reclaimed by another
  89 thread via a call to
  90 .Fn pthread_join .
  91 Alternatively,
  92 .Fn pthread_detach
  93 may be called on the thread to indicate that the system may automatically
  94 reclaim the thread storage upon exit.
  95 The
  96 .Fn pthread_attr_setdetachstate
  97 function may be used on the
  98 .Fa attr
  99 argument passed to
 100 .Fn pthread_create
 101 in order to achieve the same effect as a call to
 102 .Fn pthread_detach
 103 on the newly created thread.
 104 .Pp
 105 The signal state of the new thread is initialized as:
 106 .Bl -bullet -offset indent
 107 .It
 108 The signal mask is inherited from the creating thread.
 109 .It
 110 The set of signals pending for the new thread is empty.
 111 .El
 112 .Sh RETURN VALUES
 113 If successful,  the
 114 .Fn pthread_create
 115 function will return zero.
 116 Otherwise, an error number will be returned to
 117 indicate the error.
 118 .Sh ERRORS
 119 .Fn pthread_create
 120 will fail if:
 121 .Bl -tag -width Er
 122 .It Bq Er EAGAIN
 123 The system lacked the necessary resources to create another thread, or
 124 the system-imposed limit on the total number of threads in a process
 125 [PTHREAD_THREADS_MAX] would be exceeded.
 126 .It Bq Er EINVAL
 127 The value specified by
 128 .Fa attr
 129 is invalid.
 130 .El
 131 .Sh SEE ALSO
 132 .Xr fork 2 ,
 133 .Xr pthread_cleanup_pop 3 ,
 134 .Xr pthread_cleanup_push 3 ,
 135 .Xr pthread_detach 3 ,
 136 .Xr pthread_exit 3 ,
 137 .Xr pthread_join 3
 138 .Sh STANDARDS
 139 .Fn pthread_create
 140 conforms to
 141 .St -p1003.1-96 .