NAME

       gettid - get thread identification

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #define _GNU_SOURCE
       #include <unistd.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 in Linux 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).)

STANDARDS

       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)