journal writer: only flush kafka once per batch
This code was flushing kafka messages and waiting for the brokers on every message, instead of just doing it once per batch.
Migrated from D8803 (view on Phabricator)
This code was flushing kafka messages and waiting for the brokers on every message, instead of just doing it once per batch.
Migrated from D8803 (view on Phabricator)