Actually, that's not quite right. The sync worker will wake up the apply worker to change the state from SYNCDONE to READY. AllTablesyncsReady() checks that all tables are READY, so we need to wake up all the workers when an apply worker changes the state to READY. Each worker will then evaluate whether to restart for two_phase mode.
Right. I didn't think about the two phase case thoroughly. Waking up all apply workers can help.
Do we also need to wake up all sync workers too? Even if not, I'm not actually sure whether doing that would harm anything though.
Just asking since currently the patch wakes up all workers including sync workers if any still exists.
