Abort OE in PrepareProposal

baseapp/abci.go

@@ -413,6 +413,14 @@ func (app *BaseApp) PrepareProposal(req *abci.RequestPrepareProposal) (resp *abc
 		NextValidatorsHash: req.NextValidatorsHash,
 		AppHash:            app.LastCommitID().Hash,
 	}
+
+	// Abort any running OE so it cannot overlap with `PrepareProposal`. This could happen if optimistic
+	// `internalFinalizeBlock` from previous round takes a long time, but consensus has moved on to next round.
+	// Overlap is undesirable, since internalFinalizeBlock` and `PrepareProoposal` could share access to
+	// in-memory structs.
+	// No-op if OE is not enabled.
+	// Similar call to Abort() is done in `ProcessProposal`
+	app.optimisticExec.Abort()
 	app.setState(execModePrepareProposal, header)
 
 	// CometBFT must never call PrepareProposal with a height of 0.