email_worker calls get_async_session_factory() inside every resolve_user()
call, which creates a brand-new async engine (and thus a brand-new
connection pool) on every message. In a tight consumer loop processing
5 messages per batch, this rapidly exhausts DragonflyDB/Postgres
connection limits and manifests as ConnectionResetError.
Fix: cache the async engine in a module-level dict keyed by URL in
cartsnitch_common.database:get_async_engine(), matching the pattern
already used in receiptwitness:events.py for the Redis connection pool.
Also add pool_size=10, max_overflow=20, pool_pre_ping=True for
健壮连接管理.
Similarly, receiptwitness/queue/email.py:get_redis() was creating a new
Redis connection on every call with no pooling. Share a
ConnectionPool (max_connections=30) across all get_redis() callers.
Fixes CAR-1078
Co-Authored-By: Paperclip <noreply@paperclip.ing>
Flea Flicker