How to get the thread number and every thread's ID of a running process?

[Nan Xiao]

Hi all,

Greeting from me!

I am a new user of DragonflyBSD, and want to know if there is some
method to get the thread number and every thread's ID of a running
process? I try to explore "/proc/$pid" directory, but can't find
related information. I also can't find out-of-box API to fulfill these
functions.

Could anybody give some hints? Thanks very much in advance!

Best Regards
Nan Xiao