How to set the name of a thread in Linux pthreads?

Question

Is there any way of setting the name of a thread in Linux?

My main purpose is it would be helpful while debugging, and also nice if that name was exposed through e.g

Answer 1

Use the prctl(2) function with the option PR_SET_NAME (see the docs).

Note that old versions of the docs are a bit confusing. They say

Set the process name for the calling process

but since threads are light weight processes (LWP) on Linux, one thread is one process in this case.

You can see the thread name with ps -o cmd or with:

cat /proc/$PID/task/$TID/comm

or in between the () of cat /proc/$PID/task/$TID/stat:

4223 (kjournald) S 1 1 1 0...

or from GDB info threads between double quotes:

* 1    Thread 0x7ffff7fc7700 (LWP 6575) "kjournald" 0x00007ffff78bc30d in nanosleep () at ../sysdeps/unix/syscall-template.S:84