  We study computer systems with transactions executed on a set of shared
objects. Transactions arrive continually subjects to constrains that are framed
as an adversarial model and impose limits on the average rate of transaction
generation and the number of objects that transactions use. We show that no
deterministic distributed scheduler in the queue-free model of transaction
autonomy can provide stability for any positive rate of transaction generation.
Let a system consist of $m$ shared objects and an adversary be constrained such
that each transaction may access at most $k$ shared objects. We prove that no
scheduler can be stable if a generation rate is greater than
$\max\bigl\{\frac{2}{k+1},\frac{2}{\lfloor \sqrt{2m} \rfloor}\bigr\}$. We
develop a centralized scheduler that is stable if a transaction generation rate
is at most $\max\bigl\{\frac{1}{4k}, \frac{1}{4\lceil\sqrt{m}\rceil} \bigr\}$.
We design a distributed scheduler in the queue-based model of transaction
autonomy, in which a transaction is assigned to an individual processor, that
guarantees stability if the rate of transaction generation is less than
$\max\bigl\{ \frac{1}{6k},\frac{1}{6\lceil\sqrt{m}\rceil}\bigr\}$. For each of
the schedulers we give upper bounds on the queue size and transaction latency
in the range of rates of transaction generation for which the scheduler is
stable.
