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2019-03-06

manpages-dev

Manual pages about using GNU/Linux for development

man-pages

Linux kernel and C library user-space interface documentation

NAME

gettid - get thread identification

SYNOPSIS

#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()).

COLOPHON

This page is part of release 5.00 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 https://www.kernel.org/doc/man-pages/.
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