GETTID
Section: Linux Programmer's Manual (2)
Updated: 2020-04-11
Page Index
NAME
gettid - get thread identification
SYNOPSIS
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/types.h>
pid_t gettid(void);
DESCRIPTION
gettid()
returns the caller's thread ID (TID).
In a single-threaded process, the thread ID
is equal to the process ID (PID, as returned by
getpid(2)).
In a multithreaded process, all threads
have the same PID, but each one has a unique TID.
For further details, see the discussion of
CLONE_THREAD
in
clone(2).
RETURN VALUE
On success, returns the thread ID of the calling thread.
ERRORS
This call is always successful.
VERSIONS
The
gettid()
system call first appeared on Linux in kernel 2.4.11.
Library support was added in glibc 2.30.
(Earlier glibc versions did not provide a wrapper for this system call,
necessitating the use of
syscall(2).)
CONFORMING TO
gettid()
is Linux-specific and should not be used in programs that
are intended to be portable.
NOTES
The thread ID returned by this call is not the same thing as a
POSIX thread ID (i.e., the opaque value returned by
pthread_self(3)).
In a new thread group created by a
clone(2)
call that does not specify the
CLONE_THREAD
flag (or, equivalently, a new process created by
fork(2)),
the new process is a thread group leader,
and its thread group ID (the value returned by
getpid(2))
is the same as its thread ID (the value returned by
gettid()).
SEE ALSO
capget(2),
clone(2),
fcntl(2),
fork(2),
get_robust_list(2),
getpid(2),
ioprio_set(2),
perf_event_open(2),
sched_setaffinity(2),
sched_setparam(2),
sched_setscheduler(2),
tgkill(2),
timer_create(2)
COLOPHON
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