Cooperative Termination Protocol (CTP)
Assume coordinator includes a list of participants in Request-to-Prepare.
If a participant times-out waiting for the decision, it runs the following protocol.
1. Participant P sends Decision-Req to other participants
2. If participant Q voted No or hasn’t voted or received Abort from the coordinator, it responds Abort
3. If participant Q received Commit from the coordinator, it responds Commit.
4. If participant Q is uncertain, it responds Uncertain (or doesn’t respond at all).
If all participants are uncertain, then P remains blocked.