def METHOD_NAME(self):
    def write(conn):
        trans = conn.begin()
        conn.execute("INSERT INTO test VALUES (1, 1)")
        time.sleep(31)
        trans.commit()
    d1 = self.pool.do(write)
    def write2(conn):
        trans = conn.begin()
        conn.execute("INSERT INTO test VALUES (1, 1)")
        trans.commit()
    d2 = defer.Deferred()
    d2.addCallback(lambda _:
                   self.pool.do(write2))
    reactor.callLater(0.1, d2.callback, None)
    yield defer.DeferredList([d1, d2])