> weakref.WeakSet is not thread-safe,  which means concurrent create_task's in different threads (even on separate event loops) is not safe.

actually it looks like WeakSet is *supposed* to be thread-safe


```
import patchy

patchy.patch(
    "weakref:WeakSet._commit_removals",
    """\
    @@ -1,5 +1,10 @@
     def _commit_removals(self):
    -    l = self._pending_removals
    +    pop = self._pending_removals.pop
         discard = self.data.discard
    -    while l:
    -        discard(l.pop())
    +    while True:
    +        try:
    +            item = pop()
    +        except IndexError:
    +            return
    +        else:
    +            discard(item)
    """
)

import itertools
import asyncio
import concurrent.futures
import sys
import threading

threads = 200

def test_all_tasks_threading() -> None:
    async def foo() -> None:
        await asyncio.sleep(0)

    async def create_tasks() -> None:
        for i in range(1000):
            asyncio.create_task(foo())

        await asyncio.sleep(0)

    results = []
    with concurrent.futures.ThreadPoolExecutor(threads) as tpe:
        for f in concurrent.futures.as_completed(
            tpe.submit(asyncio.run, create_tasks()) for i in range(threads)
        ):
            results.append(f.result())
    assert results == [None] * threads


def main():
    for i in itertools.count():
        test_all_tasks_threading()
        print(f"worked {i}")
    return 0


if __name__ == "__main__":
    sys.exit(main())
```