man3/pthread_self.3

   1 .\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
   2 .\"     <mtk.manpages@gmail.com>
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .TH PTHREAD_SELF 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
   7 .SH NAME
   8 pthread_self \- obtain ID of the calling thread
   9 .SH LIBRARY
  10 POSIX threads library
  11 .RI ( libpthread ", " \-lpthread )
  12 .SH SYNOPSIS
  13 .nf
  14 .B #include <pthread.h>
  15 .PP
  16 .B pthread_t pthread_self(void);
  17 .fi
  18 .SH DESCRIPTION
  19 The
  20 .BR pthread_self ()
  21 function returns the ID of the calling thread.
  22 This is the same value that is returned in
  23 .I *thread
  24 in the
  25 .BR pthread_create (3)
  26 call that created this thread.
  27 .SH RETURN VALUE
  28 This function always succeeds, returning the calling thread's ID.
  29 .SH ERRORS
  30 This function always succeeds.
  31 .SH ATTRIBUTES
  32 For an explanation of the terms used in this section, see
  33 .BR attributes (7).
  34 .ad l
  35 .nh
  36 .TS
  37 allbox;
  38 lbx lb lb
  39 l l l.
  40 Interface       Attribute       Value
  41 T{
  42 .BR pthread_self ()
  43 T}      Thread safety   MT-Safe
  44 .TE
  45 .hy
  46 .ad
  47 .sp 1
  48 .SH STANDARDS
  49 POSIX.1-2001, POSIX.1-2008.
  50 .SH NOTES
  51 POSIX.1 allows an implementation wide freedom in choosing
  52 the type used to represent a thread ID;
  53 for example, representation using either an arithmetic type or
  54 a structure is permitted.
  55 Therefore, variables of type
  56 .I pthread_t
  57 can't portably be compared using the C equality operator (\fB==\fP);
  58 use
  59 .BR pthread_equal (3)
  60 instead.
  61 .PP
  62 Thread identifiers should be considered opaque:
  63 any attempt to use a thread ID other than in pthreads calls
  64 is nonportable and can lead to unspecified results.
  65 .PP
  66 Thread IDs are guaranteed to be unique only within a process.
  67 A thread ID may be reused after a terminated thread has been joined,
  68 or a detached thread has terminated.
  69 .PP
  70 The thread ID returned by
  71 .BR pthread_self ()
  72 is not the same thing as the kernel thread ID returned by a call to
  73 .BR gettid (2).
  74 .SH SEE ALSO
  75 .BR pthread_create (3),
  76 .BR pthread_equal (3),
  77 .BR pthreads (7)