Real-time Java scoped memory: design patterns and semantics

Pizlo, Filip; Fox, James M.; Holmes, David; Vítek, Jan

doi:10.1109/isorc.2004.1300335

Cited by 65 publications

(76 citation statements)

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“…At the core of the CD is an instance of the ScopedRunLoop pattern identified in [19]. The Runner class creates a Detector and periodically executes the detector's run() method within a scope.…”

Section: Patterns and Idiomsmentioning

confidence: 99%

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Scoped Types and Aspects for Real-Time Java

Andreae

Coady

Gibbs

et al. 2006

ECOOP 2006 – Object-Oriented Programming

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Abstract. Real-time systems are notoriously difficult to design and implement, and, as many real-time problems are safety-critical, their solutions must be reliable as well as efficient and correct. While higher-level programming models (such as the Real-Time Specification for Java) permit real-time programmers to use language features that most programmers take for granted (objects, type checking, dynamic dispatch, and memory safety) the compromises required for real-time execution, especially concerning memory allocation, can create as many problems as they solve. This paper presents Scoped Types and Aspects for Real-Time Systems (STARS) a novel programming model for real-time systems. Scoped Types give programmers a clear model of their programs' memory use, and, being statically checkable, prevent the run-time memory errors that bedevil models such as RTSJ. Our Aspects build on Scoped Types guarantees so that Real-Time concerns can be completely separated from applications' base code. Adopting the integrated Scoped Types and Aspects approach can significantly improve both the quality and performance of a real-time Java systems, resulting in simpler systems that are reliable, efficient, and correct.

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Section: Patterns and Idiomsmentioning

confidence: 99%

“…Multiscoped Object. A multiscoped object is an object which is used in several allocation contexts as defined in [19]. In the RTSJ CD the StateTable class keeps persistent state and is allocated in the area that is not reclaimed on each period.…”

Section: Patterns and Idiomsmentioning

confidence: 99%

Scoped Types and Aspects for Real-Time Java

Andreae

Coady

Gibbs

et al. 2006

ECOOP 2006 – Object-Oriented Programming

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“…Consequently, some RTSJ design patterns have been proposed in the literature [10][11][12]. Also, additional RTSJ design patterns have been discovered in the course of developing RTZen, and the main goal of this section is to describe them.…”

Section: Rtzen's Design Patternsmentioning

confidence: 99%

“…A Wedge Thread [10,11] is used to prevent the premature reclamation of a scoped memory area by controlling its lifetime. It consists of a real-time thread that enters a scope and blocks, waiting for a signal to exit the area.…”

Section: Summary Of Existing Rtsj Patternsmentioning

confidence: 99%

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RTZen: Highly Predictable, Real-Time Java Middleware for Distributed and Embedded Systems

et al. 2005

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Abstract. Distributed real-time and embedded (DRE) applications possess stringent quality of service (QoS) requirements, such as predictability, latency, and throughput constraints. Real-Time CORBA, an open middleware standard, allows DRE applications to allocate, schedule, and control resources to ensure predictable end-to-end QoS. The Real-Time Specification for Java (RTSJ) has been developed to provide extensions to Java so that it can be used for real-time systems, in order to bring Java's advantages, such as portability and ease of use, to real-time applications. In this paper, we describe RTZen, an implementation of a Real-Time CORBA Object Request Broker (ORB), designed to comply with the restrictions imposed by RTSJ. RTZen is designed to eliminate the unpredictability caused by garbage collection and improper support for thread scheduling through the use of appropriate data structures, threading models, and memory scopes. RTZen's architecture is also designed to hide the complexities of RTSJ related to distributed programming from the application developer. Empirical results show that RTZen is highly predictable and has acceptable performance. RTZen therefore demonstrates that Real-Time CORBA middleware implemented in real-time Java can meet stringent QoS requirements of DRE applications, while supporting safer, easier, cheaper, and faster development in real-time Java.

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Quantitative dynamic‐memory analysis for Java

Garbervetsky

Yovine

Braberman

et al. 2010

Concurrency and Computation

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Space-and time-predictability are hard to achieve for object-oriented languages with automated dynamicmemory management. Although there has been significant work to design APIs, such as the Real-Time Specification for Java (RTSJ), and to implement garbage collectors to enable real-time performance, quantitative space analysis is still in its infancy. This work presents the integration of a series of compiletime analysis techniques to help predicting quantitative memory usage. In particular, we focus on providing tool assistance for identifying RTSJ scoped-memory regions, their sizes, and overall memory usage. First, the tool-suite synthesizes a memory organization where regions are associated with methods. Second, it infers their sizes in parametric closed form in terms of relevant program variables. Third, it exhibits a parametric upper bound on the amount of available free memory required to execute a method. The experiments carried out with a RTSJ benchmark, a real-time aircraft collision detector, show that semiautomatic, tool-assisted generation of scoped-based code is both helpful and doable.An interesting approach to gain control on time and space is to change the memory organization model allocating objects in regions [4,5]. The Real-time Specification for Java (RTSJ) [6] supports application-level region-based memory management through ScopedMemory areas. Under suitable conditions, this environment guarantees both predictable-time operations and predictable-space occupancy at the expense of making programming more difficult. Indeed, complying with RTSJ rules complicates reusing legacy code without careful modification [7]. More importantly in practice, it forces the programmer to adopt new coding habits and to reason in a new paradigm quite different from Java. Moreover, ensuring predictability requires providing upper-bounds of region sizes.This paper presents an integration of a series of techniques and tools into a tool-suite to help developers tackling the aforementioned problems. It also explains how to use it to produce sound and predictable scope-memory managed code from conventional Java code. The tool-suite is meant to be used following the scenario depicted in Figure 1. The basic idea is to follow a two-step approach to assist programmers in generating regions. First, infer memory scopes with the aid of escape analysis [8,9]. Second, fine tune the memory layout by resorting to a region edition tool [10] and explicit program annotations.Furthermore, the tool-chain provides two unique key features, which are independent of the way objects are organized into regions. The first is the ability to produce upper bounds of region sizes as functions of program variables [11]. Such functions are used at runtime to determine the actual sizes of RTSJ memory-scopes. The second is the symbolic over-approximation of the dynamic memory footprint of a method (including its callees) [12]. This enables checking whether the method can be safely executed without running out of memory. That is, the resulting express...

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Real-time Java scoped memory: design patterns and semantics

Cited by 65 publications

References 1 publication

Scoped Types and Aspects for Real-Time Java

Scoped Types and Aspects for Real-Time Java

RTZen: Highly Predictable, Real-Time Java Middleware for Distributed and Embedded Systems

Quantitative dynamic‐memory analysis for Java

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