Monkeypatched single thread

monkeypatch.py

from google.cloud import pubsub_v1
from time import sleep
import eventlet

eventlet.monkey_patch()

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path("project123", "topic123")


def process_message(msg):
    publisher.publish(topic_path, data=msg.encode("utf-8"))


for i in range(1000):
    process_message(str(i))
    sleep(1)

You have to apply the monkey patch before imports, otherwise it doesn't take effect