B-trees and their variants are efficient data structures for finding records in a large collection (e.g., databases). The efficiency of B-trees increases when a number of users can manipulate the tree simultaneously. Many algorithms have been developed over the last three decades to achieve both concurrency and consistency in B-trees. However, current lock-based concurrency-control techniques l...

Concurrent access to shared data objects must be regulated by a concurrency control protocol to ensure correctness. Many concurrency control protocols require that a process set a lock on the data it accesses. Recently, there has been considerable interest in lock-free concurrency control algorithms. Lock-free algorithms ooer the potential for better system performance because slow or failed pr...

This work aims to establish the viability of lock-free object sharing in uniprocessor real-time systems. Naive usage of conventional lock-based object-sharing schemes in realtime systems leads to unbounded priority inversion. A priority inversion occurs when a task is blocked by a lower-priority task that is inside a critical section. Mechanisms that bound priority inversion usually entail kern...

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 lock primitives on re-entrant locks. These operators may lead to runtime errors and unwanted behavior; e.g., taking a lock without releasing it, ...

To make the real-time collaborative graphics design system more efficient, it is essential that the semantic violation problem be well solved. However, works on semantic preservation are very limited. We present the novel schema of semantic locking to prevent semantic violation. Semantic locks are classified into region lock and object lock to solve semantic violation problems at different leve...

Priority queues are an important algorithmic component and are ubiquitous in systems and software. With the rapid deployment of parallel platforms, concurrent versions of priority queues are becoming increasingly important. In this paper, we present a novel concurrent lock-free linearizable algorithm for priority queues that scales significantly better than all known (lock-based or lock-free) p...

In parallel database systems, conflicts for accesses to objects are solved through object locking. In order to acquire and release locks, in the standard implementation of a lock manager small sections of the code may be executed only by a single thread. On massively parallel shared memory machines (SMM) the serialization of these critical sections leads to serious performance degradation. We e...

This paper presents a verification technique for a concurrent Java-like language with reentrant locks. The verification technique is based on permissionaccounting separation logic. As usual, each lock is associated with a resource invariant, i.e., when acquiring the lock the resources are obtained by the thread holding the lock, and when releasing the lock, the resources are released. To accomm...

We present an integrated framework for developing realtime systems in which lock-free algorithms are employed to implement shared objects. There are two key objectives of our work. The first is to enable functionality for object sharing in lock-free real-time systems that is comparable to that in lock-based systems. Our main contribution toward this objective is an efficient approach for implem...

this study was conducted to investigate the effects of age and sex on the fleece characteristics of 40 iranian indigenous khorasan goats. goats were divided into two different sex and age (kids and adults) groups. fiber characteristics under study were: fleece weight, fiber length, lock length, fiber diameter, coefficient of fiber diameter, breaking load, resistance, elongation, hair percentage...