3PC Failure Handling
If coordinator times out before receiving Prepared from all participants, it decides to abort.
Coordinator ignores participants that don’t ack its Pre-Commit.
Participants that voted Prepared and timed out waiting for Pre-Commit or Commit use the termination protocol.
The termination protocol is where the complexity lies. (E.g. see [Bernstein, Hadzilacos, Goodman 87], Section 7.4)