Griglie ComputazionaliTransactions24 Timeout Protocol Resource Manager times out waiting for prepare message – Abort the subtransaction Since the (distributed) transaction cannot commit unless Resource Manager votes to commit, atomicity is preserved Transaction Manager times out waiting for vote message – Abort the transaction Since Transaction Manager controls decision, it can force all Resource Managers to abort, preserving atomicity Resource Manager, in prepared state, times out waiting for commit/abort message – Resource Manager blocked since it does not know Transaction Managers decision Transaction Manager might have decided commit or abort Resource Manager cannot unilaterally decide and release locks, since its decision might be contrary to Transaction Managers decision, violating atomicity – Locks cannot be released Transaction Manager times out waiting for done message – Request done message from missing Resource Manager
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