APScheduler add lots of jobs concurrently (database Jobstore) - python-3.x

Question

How can I schedule lots of APScheduler jobs (4,000+) concurrently? (I must schedule all these after certain user events.)
Iteratively calling add_job simply takes too long with many jobs. But when I try to use AsyncIOScheduler and the following async code, I don't get any added performance increase either.
NOTE: my scheduler needs to connect to a SQL jobstore via SqlAlchemy
scheduler = AsyncIOScheduler(jobstores={"default": SQLAlchemyJobStore(url="a valid db connection str")})
scheduler.start()
def schedule_jobs_quickly():
# init lots of (fake) jobs
jobs = []
for i in range(3000):
jobs.append(i)
send_time = datetime.datetime.now() + datetime.timedelta(days=2)
# try to schedule jobs concurrently
start_time = time.time()
asyncio.get_event_loop().run_until_complete(schedule_all_jobs(jobs, send_time))
duration = time.time() - start_time
print(f"Created {len(jobs)} jobs in {duration} seconds")
async def schedule_all_jobs(all_jobs, send_time):
tasks = []
for job in all_jobs:
task = asyncio.ensure_future(schedule_job(job, send_time))
tasks.append(task)
await asyncio.gather(*tasks, return_exceptions=True)
async def schedule_job(job, send_time):
scheduler.add_job(send_email_if_needed, trigger=send_time)
Result is very slow. How to speed this up?
>>> schedule_jobs_quickly()
...
Created 3000 jobs in 401.9982771873474 seconds
For comparison, this is how long it took with a BackgroundScheduler() using the default memory jobstore:
Created 3000 jobs in 0.9155495166778564 seconds
So, it seems to be the database connections that are so expensive. Maybe there's a way to create multiple jobs using the same connection, instead of re-connecting for each add_job?

Answer 1

It's not the solution I was looking for, but I decided to give up on AsyncIOScheduler and instead schedule my many tasks in a separate thread so the rest of my program could continue without being held up by all of the DB connections. Example below.
from threading import Thread
def schedule_jobs_quickly():
# init lots of (fake) jobs
jobs = []
for i in range(3000):
jobs.append(i)
send_time = datetime.datetime.now() + datetime.timedelta(days=2)
# schedule jobs in new thread
scheduler_thread = Thread(target=schedule_email_jobs, args=(email_jobs,))
scheduler_thread.start()
def schedule_email_jobs(jobs):
for job in jobs:
scheduler.add_job(send_email, trigger=send_time)
def send_email():
# sends email