Gracefully handle multiprocessing forks in _EventLoopSingleton

[tsmith023]

Closes #1309

MRE to reproduce, courtesy of @gariel ❤️

import logging
import os

from fastapi import FastAPI
from fastapi.responses import JSONResponse

from pydantic import BaseModel
import weaviate
from weaviate.classes.query import Filter


# some dependency instantiate a sync client on import/file root
client = weaviate.connect_to_local()
client.close()

app = FastAPI()
logger = logging.getLogger(__name__)

class StatusBody(BaseModel):
    collection: str
    field: str
    value: str


@app.post("/sync", response_class=JSONResponse)
async def status_sync(body: StatusBody):
    logger.info("Status endpoint")

    with weaviate.connect_to_local() as client:

        logger.info("Status got client")

        result = client.collections.get(body.collection).query.fetch_objects(
            filters=Filter.by_property(body.field).equal(body.value),
            limit=1
        )

        logger.info("Status got response")

        data = result.objects[0].properties
        logger.info(f"Status: {data}")

        return data


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=80)

and run:
gunicorn --bind=0.0.0.0:80 --workers=2 --worker-class "uvicorn.workers.UvicornWorker" --preload main:app

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 93.94%. Comparing base (3f68082) to head (d44a585).
Report is 146 commits behind head on main.

Files with missing lines	Patch %	Lines
weaviate/event_loop.py	73.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1373      +/-   ##
==========================================
- Coverage   94.38%   93.94%   -0.44%     
==========================================
  Files         220      221       +1     
  Lines       20956    21283     +327     
==========================================
+ Hits        19779    19995     +216     
- Misses       1177     1288     +111     

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[dirkkul]

Can you add a test? :)

[weaviate-git-bot]

Great to see you again! Thanks for the contribution.

beep boop - the Weaviate bot 👋🤖

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