Retrieving document snapshots concurrently from different threads leads to a deadlock

[sergeyle]

Calling get() to retrieve a document snapshot concurrently from different threads reliably leads to a deadlock. This was attempted on an M1 Mac and a GCE Cloud Console Linux.

This was tried on google-cloud-firestore=(2.15.0|2.16.0)

Code to reproduce the bug:

import threading
import firebase_admin
from firebase_admin import credentials, firestore


__app = firebase_admin.initialize_app(credentials.ApplicationDefault())

def query_firestore(docid):
    db = firestore.client(__app)
    coll = db.collection("mycollection")
    try:
        print("About to query firestore")
        doc = coll.document(docid).get().to_dict()
        # The flow never reaches here.
        print(f"Document data: {doc}")
    except Exception as e:
        print(f"Error querying Firestore: {e}")


def start_threads(n, docid):
    threads = []
    for _ in range(n):
        thread = threading.Thread(target=query_firestore, args=(docid,))
        threads.append(thread)
        thread.start()
    # Wait for all threads to complete
    for thread in threads:
        thread.join()

if __name__ == "__main__":
    N = 5  # Number of threads
    docid = "1234"
    start_threads(N, docid)