cannot use other functions to apply a port without fastapi

[aLowMagic]

when i use this docker to run a fastapi like:

@app.get("/testyf")
async def root():
    return {"message": "Hello World"}

it runs fine, but if i insert a socket listener like;

class Listener(threading.Thread):
    def __init__(self, port):
        threading.Thread.__init__(self)
        self.port = port
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.sock.settimeout(10000000)
        self.sock.bind(("0.0.0.0", port))
        self.sock.listen(0)
    def run(self):
        print("listener started")
        self.sock.accept()


lst  = Listener(9011)   # create a listen thread
lst.start() # then start

then it will not run and the errorlog is:

[2021-09-06 08:05:23 +0000] [10] [ERROR] Exception in worker process
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/gunicorn/arbiter.py", line 583, in spawn_worker
    worker.init_process()
  File "/usr/local/lib/python3.7/site-packages/uvicorn/workers.py", line 57, in init_process
    super(UvicornWorker, self).init_process()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/base.py", line 119, in init_process
    self.load_wsgi()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/base.py", line 144, in load_wsgi
    self.wsgi = self.app.wsgi()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/base.py", line 67, in wsgi
    self.callable = self.load()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/wsgiapp.py", line 49, in load
    return self.load_wsgiapp()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/wsgiapp.py", line 39, in load_wsgiapp
    return util.import_app(self.app_uri)
  File "/usr/local/lib/python3.7/site-packages/gunicorn/util.py", line 358, in import_app
    mod = importlib.import_module(module)
  File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/app/app/main.py", line 35, in <module>
    lst  = Listener(9011)   # create a listen thread
  File "/app/app/main.py", line 28, in __init__
    self.sock.bind(("0.0.0.0", port))
OSError: [Errno 98] Address already in use

(actually, the socket is a prometheus method)
does someone have idea?