Ray ObjectRet doesn't seems to be released from server side

High: It blocks me to complete my task.

I am very new to ray. I just submit a function to a ray cluster around 200 times, each time with a different parameter. My code hangs after a few submits (The behavior is not always reproducible) . After SIGHUP, I notice the progress hangs at Worker._release_server.
code details:
def _release_server(self, id: bytes) → None:
if self.data_client is not None:
logger.debug(f"Releasing {id.hex()}")

My code is very simple as follows:
def get_data(date):

ref_jobs = [get_data.remote(date) for date in dates]
results = ray.get(ref_jobs)

get_data calls a function imported from my personal project which is uploaded through py_modules.

Probably a bug or you need to modify your program. Can you post a GitHub issue with a self-contained reproduction script? As is, I don’t think we have enough information to help you.