Memory leak or am I missing an option?

[brantleyp1]

I'm running into an issue trying to make a script using aiosmtpd to listen for localhost mail to forward to SES. Running on AWS instances if I send too many messages to this server script the memory grows and eventually takes down the instance. I'm testing on a t2.medium running Amazon Linux 2.

Sample code, with some logging and most of the handler_* code removed for brevity:

class EmailHandler:
    async def handle_MAIL(self, server, session, envelope, address, rcpt_options):
    async def handle_RCPT(self, server, session, envelope, address, rcpt_options):
    async def handle_DATA(self, server, session, envelope):
        if config['test_mode']:
            logger.info('From: ' + envelope.mail_from + ' To: ' + ','.join(envelope.rcpt_tos) + ' MessageId: Running in test mode - not sending to SES')
            logger.debug('Running in test mode - SES JSON payload:\n' + json.dumps(payload,indent=4))
            return '250 Message accepted for delivery'
            cancel_tasks(stop_loop=False)
        elif not config['test_mode']:
            try:
                response = self.__ses.send_email( **payload )
                logger.info('From: ' + envelope.mail_from + ' To: ' + ','.join(envelope.rcpt_tos) + ' MessageId: ' + str(response['MessageId']))
                return '250 Message accepted for delivery'
            except Exception as err:
                logger.error('From: ' + envelope.mail_from + ' To: ' + ','.join(envelope.rcpt_tos) + ' ERROR: ' + str(err))
                return '554 Transaction has failed'

async def amain(loop):
    handler = EmailHandler()
    controller = Controller(handler, hostname=config['server']['host'], port=config['server']['port'])
    controller.start()


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.create_task(amain(loop=loop))
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass

The issue I'm seeing is if I have this script running in a test mode that dumps the json to a log instead of SES, when loop sending messages testing volume the script quickly grows infinitely.

If I run a loop, giving a moderately sized attachment and some lorem ipsum text for a body, something like:

while true; do mail -S smtp=localhost:8025 -s "$(date)" -a 20meg.txt -r my@example.net my@example.net < 10k.txt; sleep 1; done

Looking at the VmRSS of the PID, the script initializes around 40meg of memory. If I let it run 100 iterations, it will grow to almost 2 gig of memory. But if I extend the sleep time out to 5 seconds or more, it starts at 40meg and never (at least 300 iterations) grows above 200meg.