Faulthandler output should include the thread name

[spacemanspiff2007]

Feature or enhancement

Proposal:

Currently faulthandler just dumps the thread id.
It would be nice if the thread name would also be part of the output since this makes debugging much easier

Current output

Thread 0x00003b9c (most recent call first):
  File "C:\ProgramFiles\Python\Python312\Lib\concurrent\futures\thread.py", line 89 in _worker
  File "C:\ProgramFiles\Python\Python312\Lib\threading.py", line 1012 in run
  File "C:\ProgramFiles\Python\Python312\Lib\threading.py", line 1075 in _bootstrap_inner
  File "C:\ProgramFiles\Python\Python312\Lib\threading.py", line 1032 in _bootstrap
...

Better output with thread name in square brackets

Thread 0x00003b9c [Thread pool worker 1] (most recent call first):
  File "C:\ProgramFiles\Python\Python312\Lib\concurrent\futures\thread.py", line 89 in _worker
  File "C:\ProgramFiles\Python\Python312\Lib\threading.py", line 1012 in run
  File "C:\ProgramFiles\Python\Python312\Lib\threading.py", line 1075 in _bootstrap_inner
  File "C:\ProgramFiles\Python\Python312\Lib\threading.py", line 1032 in _bootstrap
...

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-125434: Display thread name in faulthandler #132016
• gh-125434: Fix building on OpenBSD #132393

[rruuaanng]

Sorry, It seems that there is no thread name member in PyThreadState :(. In my opinion, The thread name does not make much sense, although it is more convenient for debugging.
(Maybe I didn't find it).

[spacemanspiff2007]

If it's not there it obviously can't be included. Thank you very much for looking!
I'm debugging an asyncio applications which also uses a thread pool.
Since I'm only interested in the threads from the thread pool the thread name would have been a very easy and convenient way to identify these threads.

[vstinner]

I don't think that we can implement this feature.

Sadly, faulthandler is very low-level. It doesn't have access to threading.Threading.name attribute. It cannot import a module or do complex operation.

faulthandler is called in a signal handler, only "async signal-safe" function can be used, memory can only be allocated on the stack (not on the heap).

I suggest to close this issue as "won't fix".

[picnixz]

I think I'll follow Victor's call. I had a quick look at the code to see how we could make it include the thread name but I don't think it's feasible.

One possibility is to carry the latter everywhere but since only stack-allocated memory can be used I really don't think we can have a simple fix.

[vstinner]

One approach would be to set the thread name in the OS: #59705 and then retrieve the thread name from the OS. It might work if retrieving the name is safe in a signal handler.

[vstinner]

I wrote a change to set the thread name to the operating system: #127338

[vstinner]

I wrote PR gh-132016 to display the thread native name in faulthandler.