Modules as values in a persistent object store

Journal ArticleWe report on an object manager (OM) providing persistent implementations for C ++ classes. Our OM generalizes this problem to that of managing persistent modules, where the module concept is an abstract data type (ADT). This approach permits a powerful suite of module manipulation operations to be applied uniformly to modules of many provenances, including non-class based entities such as conventional object files, application libraries, and shared system libraries. OMOS, a generalized linker and loader, plays a central role in our OM. Class implementations are represented by OMOS modules, which in turn are constructed from OMOS meta-objects encapsulating linkage blueprints. We cleanly solve the problems of (i) logically (but not physically) including executable object files in our OM, (ii) reconciling class inheritance history and linkage history, and (iii) supporting alternative implementations of a class, for client interoperability or version control

Execution Performance Issues in Full-Text Information Retrieval

The task of an information retrieval system is to identify documents that will satisfy a user’s information need. Effective fulfillment of this task has long been an active area of research, leading to sophisticated retrieval models for representing information content in documents and queries and measuring similarity between the two. The maturity and proven effectiveness of these systems has resulted in demand for increased capacity, performance, scalability, and functionality, especially as information retrieval is integrated into more traditional database management environments. In this dissertation we explore a number of functionality and performance issues in information retrieval. First, we consider creation and modification of the document collection, concentrating on management of the inverted file index. An inverted file architecture based on a persistent object store is described and experimental results are presented for inverted file creation and modification. Our architecture provides performance that scales well with document collection size and the database features supported by the persistent object store provide many solutions to issues that arise during integration of information retrieval into vii more general database environments. We then turn to query evaluation speed and introduce a new optimization technique for statistical ranking retrieval systems that support structured queries. Experimental results from a variety of query sets show that execution time can be reduced by more than 50% with no noticeable impact on retrieval effectiveness, making these more complex retrieval models attractive alternatives for environments that demand high performance

CAPre: Code-Analysis based Prefetching for Persistent object stores

Data prefetching aims to improve access times to data storage systems by predicting data records that are likely to be accessed by subsequent requests and retrieving them into a memory cache before they are needed. In the case of Persistent Object Stores, previous approaches to prefetching have been based on predictions made through analysis of the store’s schema, which generates rigid predictions, or monitoring access patterns to the store while applications are executed, which introduces memory and/or computation overhead. In this paper, we present CAPre, a novel prefetching system for Persistent Object Stores based on static code analysis of object-oriented applications. CAPre generates the predictions at compile-time and does not introduce any overhead to the application execution. Moreover, CAPre is able to predict large amounts of objects that will be accessed in the near future, thus enabling the object store to perform parallel prefetching if the objects are distributed, in a much more aggressive way than in schema-based prediction algorithms. We integrate CAPre into a distributed Persistent Object Store and run a series of experiments that show that it can reduce the execution time of applications from 9% to over 50%, depending on the nature of the application and its persistent data model.This work has been supported by the European Union’s Horizon 2020 research and innovation program under the BigStorage European Training Network (ETN) (grant H2020-MSCA-ITN-2014- 642963), the Spanish Ministry of Science and Innovation (contract TIN2015-65316) and the Generalitat de Catalunya, Spain (contract 2014-SGR-1051).Peer ReviewedPostprint (author's final draft

Cricket: A Mapped, Persistent Object Store

This paper describes Cricket, a new database storage system that is intended to be used as a platform for design environments and persistent programming languages. Cricket uses the memory management primitives of the Mach operating system to provide the abstraction of a shared, transactional single-level store that can be directly accessed by user applications. In this paper, we present the design and motivation for Cricket. We also present some initial performance results which show that, for its intended applications, Cricket can provide better performance than a general-purpose database storage system

On the integration of concurrency, distribution and persistence

The principal tenet of the persistence model is that it abstracts over all the physical properties of data such as how long it is stored, where it is stored, how it is stored, what form it is kept in and who is using it. Experience with programming systems which support orthogonal persistence has shown that the simpler semantics and reduced complexity can often lead to a significant reduction in software production costs. Persistent systems are relatively new and it is not yet clear which of the many models of concurrency and distribution best suit the persistence paradigm. Previous work in this area has tended to build one chosen model into the system which may then only be applicable to a particular set of problems. This thesis challenges the orthodoxy by designing a persistent framework in which all models of concurrency and distribution can be integrated in an add-on fashion. The provision of such a framework is complicated by a tension between the conceptual ideas of persistence and the intrinsics of concurrency and distribution. The approach taken is to integrate the spectra of concurrency and distribution abstractions into the persistence model in a manner that does not prevent the user from being able to reason about program behaviour. As examples of the reference model a number of different styles of concurrency and distribution have been designed and incorporated into the persistent programming system Napier88. A detailed treatment of these models and their implementations is given

The role of memory in the philosophy of personality

Thesis (M.A.)--Boston University, 194