Why does a kernel thread have a PID?

Question

In Linux, a kernel thread have a PID:

Why is that? Is a kernel thread considered to be a process? And does a "normal" thread also have a PID?

http://opensourceforu.com/2011/08/light-weight-processes-dissecting-linux-threads/ should help — Munir, Jun 20 '17 at 00:56
See also https://unix.stackexchange.com/questions/31595/are-kernel-threads-really-kernel-processes — Anthony Geoghegan, Jun 20 '17 at 09:09

alzee · Answer 1 · 2017-06-20T00:36:27.117

6

They are poorly named. Kernel threads in linux are processes (not actual threads) that run in kernel space rather than user space.

edited Jun 20 '17 at 00:36

answered Jun 20 '17 at 00:26

alzee

A process have many threads, does a kernel thread have many threads also? – paul Jun 20 '17 at 02:55
@paul Related: https://stackoverflow.com/q/34959506/4941495 – Kusalananda Jun 20 '17 at 06:09
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Kernel threads do not run in their own address space. Since the usual definition of a thread (vs. a process) is that related threads are executed in a shared address space, I think thread is a more appropriate term than process here. – Johan Myréen Jun 20 '17 at 07:08
@Johan Myréen A kernel thread has a PID as I have shown, but does a "normal" thread also have a PID? – paul Jun 20 '17 at 18:19
@paul - "Normal" thread too has a PID, which is inherited from the creator process/thread (the one that called pthread_create() to launch it). – FooF Apr 27 '20 at 08:29

1 Answers1