In two-phase commit, every participant voted yes, then the coordinator crashed before sending its decision to anyone. What may a participant do?

Options

• ✗ Commit after a timeout, since everyone voted yes
• ✗ Abort after a timeout to release its locks
• ✓ Nothing on its own: keep its locks and wait until it learns the decision Correct
• ✗ Ask a majority of participants to vote again

Why

The coordinator may have logged "commit" just before crashing, or decided to abort, so committing or aborting alone could break atomicity. Asking other participants helps only if one of them heard the decision. This is the blocking problem; consensus-based commit (as in Spanner) replicates the decision so it survives the coordinator.

Review this in your daily deck → All cards in Coordination