Making stronger and flexible the single parent rule in the real-time specification of Java

ABSTRACT

Java is the ideal language for developing embedded distributed real-time applications. However, most Java implementations and tools were designed for workstations and have limitations due to that heritage. Special tools are required to support deployment and effect better integration with target hardware and the real-time requirements of embedded systems. The Real-time Specification for Java (RTSJ) extends the Java memory model through immortal and scoped memory regions to reduce the timing-indeterminism caused by garbage collection. The goal of this paper is to improve the predictability and performance of real-time Java applications according to the new RTSJ Specification Request (JSR-282) 2 and 3 enhancements. The single parent rule, that RTSJ introduces, prevents cyclic use of scoped memory regions. But, since this rule cannot be statically enforced, induces run-time overhead and even nondeterministic behavior of applications (due to race conditions). This paper modifies the single parent rule making it stronger, and allows it violation under some conditions in order to have bidirectional references among objects within two different scopes.

REFERENCES

• 1: Pablo Basanta-Val , Marisol García-Valls , Iria Estevez-Ayres , Carlos Delgado-Kloos, Extended portal: violating the assignment rule and enforcing the single parent rule, Proceedings of the 4th international workshop on Java technologies for real-time and embedded systems, October 11-13, 2006, Paris, France [doi>10.1145/1167999.1168006]
• 2: P. Basanta-Val, M.l García-Valls, I. Estévez-Ayres. "No Heap Remote Objects: Leaving Out Garbage Collection at the Server Side". OTM Workshops 2004: Workshop on Java Technologies for Real-Time and Embedded Systems. 2004.
• 3: E. G. Benowitz, A. F. Niessner. "A Patterns Catalog for RTSJ Software Designs". OTM Workshops 2003: Workshop on Java Technologies for Real-Time and Embedded Systems.
• 4: Greg Bollella , Tim Canham , Vanessa Carson , Virgil Champlin , Daniel Dvorak , Brian Giovannoni , Mark Indictor , Kenny Meyer , Alex Murray , Kirk Reinholtz, Programming with non-heap memory in the real time specification for Java, Companion of the 18th annual ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications, October 26-30, 2003, Anaheim, CA, USA [doi>10.1145/949344.949443]
• 5: A. Borg, A. J. Wellings. "Reference Objects for RTSJ Memory Areas". OTM Workshops 2003: Workshop on Java Technologies for Real-Time and Embedded Systems.
• 6: A. Corsaro, C. Santoro. "Design Patterns for RTSJ Application Development". OTM Workshops 2004: Workshop on Java Technologies for Real-Time and Embedded Systems.
• 7: Angelo Corsaro , Ron K. Cytron, Efficient memory-reference checks for real-time java, Proceedings of the 2003 ACM SIGPLAN conference on Language, compiler, and tool for embedded systems, June 11-13, 2003, San Diego, California, USA
• 8: P. C. Dibble. "Real-time Java Platform Programming". Prentice Hall. 2002.
• 9: M. Teresa Higuera-Toledano, Towards an Understanding of the Behavior of the Single Parent Rule in the RTSJ Scoped Memory Model, Proceedings of the 11th IEEE Real Time on Embedded Technology and Applications Symposium, p.470-479, March 07-10, 2005 [doi>10.1109/RTAS.2005.56]
• 10: M. Teresa Higuera-Toledano, Name-Based Write Barriers in Real-Time Java, Proceedings of the 7th IEEE International Conference on Computer and Information Technology, p.781-786, October 16-19, 2007
• 11: M. Teresa Higuera-Toledano, Allowing Cycle References by Introducing Controlled Violations of the Assignment Rules in Real-Time Java, Proceedings of the 2008 11th IEEE Symposium on Object Oriented Real-Time Distributed Computing (ISORC), p.463-467, May 05-07, 2008 [doi>10.1109/ISORC.2008.48]
• 12: JSR-282. "RTSJ version 1.1". Available on-line at http://www.jcp.org/en/jsr/detail?id=282
• 13: F. Pizlo, J. M. Fox, D. Holmes, J. Vitek. "Real-Time Java Scoped Memory: Design Patterns and Semantics". In Proc. 7th IEEE International Symposium on Object Oriented Real-Time Distributed Computing, (ISORC 2004)
• 14: Krishna Raman , Yue Zhang , Mark Panahi , Juan A. Colmenares , Raymond Klefstad, Patterns and Tools for Achieving Predictability and Performance with Real-Time Java, Proceedings of the 11th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, p.247-253, August 17-19, 2005 [doi>10.1109/RTCSA.2005.68]
• 15: RTJEG. "The Real-time Java Specification". Version 1.0.1(b). Available on-line at http://www.rtj.org
• 16: Timesys. "JTIME RTSJ 1.0 Extensions User Guide" Available on-line at http://www.timesys.com

INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.3 Language Constructs and Features

General Terms:
Algorithms, Management, Measurement, Performance

Keywords:
illegal assignments, real-time Java, reference-counting collection, scoped-regions, single parent rule, write-barriers