Issue with watchdog PollingObserver missing events when removing files

watchdog_polling_repro.py

# Reproduction for https://github.com/gorakhargosh/watchdog/issues/992

from tempfile import TemporaryDirectory
import time
import os
import os.path
from multiprocessing import Process, Queue
from pathlib import Path

from watchdog.observers.polling import PollingObserver
from watchdog.events import FileSystemEventHandler

TOTAL_FILES = 100


def generate_events(tmp_dir, q):
    for i in range(1, TOTAL_FILES + 1):
        time.sleep(0.1)
        p = Path(os.path.join(tmp_dir, f"{i}"))
        p.touch()
        inode = os.stat(p).st_ino
        q.put(("created", i, inode))
    time.sleep(2)
    q.put(("DONE", None, None))


class Event(FileSystemEventHandler):
    def __init__(self, queue) -> None:
        self._processed = 0
        self._queue = queue

    def dispatch(self, event):
        print(f"Event: {event}")
        if event.is_directory:
            return
        if event.event_type not in ("modified", "created"):
            return
        if event.src_path.endswith(".processed"):
            return
        dst_path = event.src_path + ".processed"
        Path(dst_path).touch()
        inode = os.stat(dst_path).st_ino
        i = int(event.src_path.split("/")[-1])
        if os.path.exists(event.src_path):
            os.remove(event.src_path)
            self._processed += 1
            q.put(("processed", i, inode))
        else:
            q.put(("processed-not-found", i, inode))

with TemporaryDirectory() as tmp_dir:
    print(f"TMP_DIR: {tmp_dir}")

    q = Queue()
    observer = PollingObserver(timeout=1)
    observer.schedule(Event(queue=q), path=tmp_dir)
    observer.start()

    p = Process(target=generate_events, args=(tmp_dir, q))
    p.start()
    _seen = {"processed": list(), "processed-not-found": list(), "created": list()}
    while True:
        ev, i, inode = q.get()
        if ev == "DONE":
            break
        print((ev, i, inode))
        _seen[ev].append(i)
    print(f"Created {len(_seen['created'])} files: {_seen['created']}")
    print(f"Processed {len(_seen['processed'])} files: {_seen['processed']}")
    print(f"Not found {len(_seen['processed-not-found'])} files: {_seen['processed-not-found']}")
    missing = set(_seen["created"]) - set(_seen["processed"])
    print(f"Missing processing: {missing}")
    not_seen_at_all = set(_seen["created"]) - set(_seen["processed"]) - set(_seen["processed-not-found"])
    print(f"Not seen at all: {not_seen_at_all}")
    p.join()
    print("File creator process finished")
    print("Stopping observer")
    observer.stop()