The exibility of nested transactions is generally provided at the expenses of a more complex locking mechanism which must deal with expensive lock inheritance. In this paper, we give a solution for eecient lock inheritance. Our solution does not change the original nested transaction model but does revisit its locking rules using set-oriented semantics. This allows us to trade the cost of lock ...

Fine-grained lock protocols with lock modes and lock granules adjusted to the various XML processing models, allow for highly concurrent transaction processing on XML trees, but require locking facilities that efficiently support large and deep hierarchies with varying fan-out characteristics. We discuss these and also further requirements like prefix-based node labels, and present a lock manag...

Based on loosely coupled services in an XML engine, we describe how to realize fine-grained lock protocols, which can guarantee transaction isolation for applications using different language models. We illustrate the superiority of the taDOM lock protocol family and its tailormade lock modes and lock granules adjusted to the XML language model. We emphasize the importance of a prefix-based nod...

The 28 lock and dams sites on the upper Mississippi River is currently central to transporting U.S. agricultural commodities to the world market. This aging lock and dam system and slow double lockage process at the 600-foot locks have generated concern about its navigational efficiency. The objective of this study is to examine the determinants of delay occurred at the lock and dam system on t...

Synchronization overhead may limit the number of applications that can take advantage of a shared-memory abstraction on top of emerging network of workstation organizations. While the programmer could spend additional efforts into getting rid of such overhead by restructuring the computation, this paper focuses on a simpler approach where the overhead of lock operations is hidden through lock p...

The idea of data transfer by physically severed connections has been applied in a simple realization of the Lock-Keeper technology, the SingleGate Lock Keeper system. By means of it, the possibility of direct attacks to a protected network can be eliminated entirely and data can be exchanged between two networks through a completely secure and reliable way. As an advanced implementation of this...

The exibility of nested transactions is generally provided at the expense of a more complex locking mechanism which must deal with expensive lock inheritance. In this paper, we give a solution for eecient lock inheritance. Our solution does not change the original nested transactions model but does revisit its locking rules using set-oriented semantics. This allows us to trade the cost of lock ...

The choice of lock objects in concurrent programs can affect both performance and correctness, a burden of complexity for programmers. Recently, various automated lock allocation and assignment techniques have been proposed, each aiming primarily to minimize the number of conflicts between critical sections. However, practical performance depends on a number of important factors, including the ...

There are many mechanisms for concurrency control in high-level programming languages. In Java, the original mechanism for concurrency control, based on synchronized blocks, is lexically scoped. For more flexible control, Java 5 introduced non-lexical operators, supporting lock primitives on re-entrant locks. These operators may lead to run-time errors and unwanted behavior; e.g., taking a lock...