gettid(2) — Linux manual page


GETTID(2)                 Linux Programmer's Manual                GETTID(2)

NAME         top

       gettid - get thread identification

SYNOPSIS         top

       #define _GNU_SOURCE
       #include <unistd.h>
       #include <sys/types.h>

       pid_t gettid(void);

DESCRIPTION         top

       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         top

       On success, returns the thread ID of the calling thread.

ERRORS         top

       This call is always successful.

VERSIONS         top

       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

CONFORMING TO         top

       gettid() is Linux-specific and should not be used in programs that
       are intended to be portable.

NOTES         top

       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         top

       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         top

       This page is part of release 5.07 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                            2020-04-11                        GETTID(2)

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