@Override
  public void executeOnAllQueueServers(Op op) {
    if (queueManager == null) {
      throw new SubscriptionNotEnabledException();
    }

    RuntimeException lastException = null;

    final QueueConnections connections = queueManager.getAllConnectionsNoWait();
    final Connection primary = connections.getPrimary();
    if (primary != null) {
      try {
        executeWithPossibleReAuthentication(primary, op);
      } catch (Exception e) {
        try {
          handleException(e, primary, 0, false);
        } catch (RuntimeException e2) {
          lastException = e2;
        }
      }
    }

    final List<Connection> backups = connections.getBackups();
    for (final Connection connection : backups) {
      try {
        executeWithPossibleReAuthentication(connection, op);
      } catch (Exception e) {
        try {
          handleException(e, connection, 0, false);
        } catch (RuntimeException e2) {
          lastException = e2;
        }
      }
    }

    if (lastException != null) {
      throw lastException;
    }
  }
execute the given op on the given server. If the server cannot be reached, sends a
TXFailoverOp, then retries the given op

@param loc the server to execute the op on
@param op the op to execute
@return the result of execution
geode-core/src/main/java/org/apache/geode/cache/client/internal/OpExecutorImpl.java