I'm trying to run a shuttle following the usage guide in https://github.com/farcasterxyz/hub-monorepo/tree/main/packages/shuttle, but failed to perform reconciliation/backfill task. 

The process looks like hanging there after printing the log "Starting worker connecting to: postgres://shuttle ..... "

The connections to database, redis and hub should be ok because syncing messages from the event stream works fine.

Can anyone tell me how to resolve this issue?

Finally got it worked. I have to start another process with "yarn start backfill" at the same time so that the worker can receive tasks to execute.

I can only say that these synchronization programs aren't great. Its predecessor, the Replicator, had such a frustrating design that data synchronization was a real headache.