Possible stale lock when the primary owner leaves during rebalance ------------------------------------------------------------------ Key: ISPN-4546 URL: https://issues.jboss.org/browse/ISPN-4546 Project: Infinispan Issue Type: Bug Components: Core, State Transfer Affects Versions: 7.0.0.Alpha5 Reporter: Dan Berindei Assignee: Dan Berindei Priority: Critical Fix For: 7.2.0.CR1 Topology T: coordinator = A, owners(k) = [C, D], pending_owners(k) = null B sends prepareCommand(tx1, put(k, v)) to C, D D adds backup locks and replies C acquires lock, ready to send reply to B A starts installing topology T+1: owners(k) = [C, D], pending_owners(k) = [C, E] A, C and E install topology T+1, B and D do not E requests and receives tx data from C, including tx1 C leaves B sees a SuspectException, sends rollbackCommand(tx1) to C, D D removes tx1 C has left, but is ignored B reports to the user that the tx has been rolled back B and D install topology T+1 (optional) A starts installing topology T+2: owners(k) = [D], pending_owners(k) = [E] A, B, D, E all install topology T+2 E requests and receives state from D, but it does not remove tx1 A starts installing topology T+3: owners(k) = [E], pending_owners(k) = null E now has a stale backup lock on k It seems very hard to reproduce in production: C would have to leave soon enough so that B and D haven't received the T+1 topology yet, but late enough for it to send its transaction data to E. A possible solution would be to catch any SuspectException during prepare/commit/rollback (without ignoring leavers), wait for a new topology, and replicate the command again on the new owners. Obviously, this wouldn't work with asynchronous prepare/commit/rollback.