A real-time garbage collector with low overhead and consistent utilization

ABSTRACT

Now that the use of garbage collection in languages like Java is becoming widely accepted due to the safety and software engineering benefits it provides, there is significant interest in applying garbage collection to hard real-time systems. Past approaches have generally suffered from one of two major flaws: either they were not provably real-time, or they imposed large space overheads to meet the real-time bounds. We present a mostly non-moving, dynamically defragmenting collector that overcomes both of these limitations: by avoiding copying in most cases, space requirements are kept low; and by fully incrementalizing the collector we are able to meet real-time bounds. We implemented our algorithm in the Jikes RVM and show that at real-time resolution we are able to obtain mutator utilization rates of 45% with only 1.6--2.5 times the actual space required by the application, a factor of 4 improvement in utilization over the best previously published results. Defragmentation causes no more than 4% of the traced data to be copied.

REFERENCES

• 1: B. Alpern , C. R. Attanasio , J. J. Barton , M. G. Burke , P. Cheng , J.-D. Choi , A. Cocchi , S. J. Fink , D. Grove , M. Hind , S. F. Hummel , D. Lieber , V. Litvinov , M. F. Mergen , T. Ngo , J. R. Russell , V. Sarkar , M. J. Serrano , J. C. Shepherd , S. E. Smith , V. C. Sreedhar , H. Srinivasan , J. Whaley, The Jalapeño virtual machine, IBM Systems Journal, v.39 n.1, p.211-238, January 2000
• 2: A. W. Appel , J. R. Ellis , K. Li, Real-time concurrent collection on stock multiprocessors, Proceedings of the ACM SIGPLAN 1988 conference on Programming Language design and Implementation, p.11-20, June 20-24, 1988, Atlanta, Georgia, United States
• 3: Matthew Arnold , Barbara G. Ryder, Thin Guards: A Simple and Effective Technique for Reducing the Penalty of Dynamic Class Loading, Proceedings of the 16th European Conference on Object-Oriented Programming, p.498-524, June 10-14, 2002
• 4: David F. Bacon , Stephen J. Fink , David Grove, Space- and Time-Efficient Implementation of the Java Object Model, Proceedings of the 16th European Conference on Object-Oriented Programming, p.111-132, June 10-14, 2002
• 5: Henry G. Baker, Jr., List processing in real time on a serial computer, Communications of the ACM, v.21 n.4, p.280-294, April 1978 [doi>10.1145/359460.359470]
• 6: Henry G. Baker, The treadmill: real-time garbage collection without motion sickness, ACM SIGPLAN Notices, v.27 n.3, p.66-70, March 1992 [doi>10.1145/130854.130862]
• 7: Ori Ben-Yitzhak , Irit Goft , Elliot K. Kolodner , Kean Kuiper , Victor Leikehman, An algorithm for parallel incremental compaction, Proceedings of the 3rd international symposium on Memory management, June 20-21, 2002, Berlin, Germany
• 8: Stephen M Blackburn , Richard Jones , Kathryn S. McKinley , J Eliot B Moss, Beltway: getting around garbage collection gridlock, Proceedings of the ACM SIGPLAN 2002 Conference on Programming language design and implementation, June 17-19, 2002, Berlin, Germany
• 9: James Gosling , Greg Bollella, The Real-Time Specification for Java, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 2000
• 10: Rodney A. Brooks, Trading data space for reduced time and code space in real-time garbage collection on stock hardware, Proceedings of the 1984 ACM Symposium on LISP and functional programming, p.256-262, August 06-08, 1984, Austin, Texas, United States [doi>10.1145/800055.802042]
• 11: A. M. Cheadle , A. J. Field , S. Marlow , S. L. Peyton Jones , R. L. While, Non-stop Haskell, Proceedings of the fifth ACM SIGPLAN international conference on Functional programming, p.257-267, September 2000
• 12: Perry Cheng , Guy E. Blelloch, A parallel, real-time garbage collector, Proceedings of the ACM SIGPLAN 2001 conference on Programming language design and implementation, p.125-136, June 2001, Snowbird, Utah, United States
• 13: Perry Cheng , Robert Harper , Peter Lee, Generational stack collection and profile-driven pretenuring, Proceedings of the ACM SIGPLAN 1998 conference on Programming language design and implementation, p.162-173, June 17-19, 1998, Montreal, Quebec, Canada
• 14: R. Dimpsey , R. Arora , K. Kuiper, Java server performance: a case study of building efficient, scalable Jvms, IBM Systems Journal, v.39 n.1, p.151-174, January 2000
• 15: Henriksson, R. Scheduling Garbage Collection in Embedded Systems. PhD thesis, Lund Institute of Technology, July 1998.
• 16: Richard L. Hudson , J. Eliot B. Moss, Incremental Collection of Mature Objects, Proceedings of the International Workshop on Memory Management, p.388-403, September 17-19, 1992
• 17: Mark Stuart Johnstone , Paul R. Wilson, Non-compacting memory allocation and real-time garbage collection, 1997
• 18: Joseph, M., and Pandya, P. K. Finding response times in a real-time system. Computer Journal 29, 5 (1986), 390--395.
• 19: Martin Larose , Marc Feeley, A compacting incremental collector and its performance in a production quality compiler, ACM SIGPLAN Notices, v.34 n.3, p.1-9, March 1999
• 20: David A. Moon, Garbage collection in a large LISP system, Proceedings of the 1984 ACM Symposium on LISP and functional programming, p.235-246, August 06-08, 1984, Austin, Texas, United States [doi>10.1145/800055.802040]
• 21: Scott Nettles , James O'Toole, Real-time replication garbage collection, ACM SIGPLAN Notices, v.28 n.6, p.217-226, June 1993
• 22: S. C. North , J. H. Reppy, Concurrent garbage collection on stock hardware, Proc. of a conference on Functional programming languages and computer architecture, p.113-133, October 1987, Portland, Oregon, United States
• 23: Fridtjof Siebert, Eliminating external fragmentation in a non-moving garbage collector for Java, Proceedings of the 2000 international conference on Compilers, architecture, and synthesis for embedded systems, p.9-17, November 17-19, 2000, San Jose, California, United States [doi>10.1145/354880.354883]
• 24: T. Yuasa, Real-time garbage collection on general-purpose machines, Journal of Systems and Software, v.11 n.3, p.181-198, Mar. 1990 [doi>10.1016/0164-1212(90)90084-Y]
• 25: Zorn, B. Barrier methods for garbage collection. Tech. Rep. CU-CS-494-90, University of Colorado at Boulder, 1990.

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.3 SPECIAL-PURPOSE AND APPLICATION-BASED SYSTEMS

Additional Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.2 Language Classifications
      D.3.4 Processors
          Subjects: Memory management (garbage collection)

General Terms:
Algorithms, Languages, Measurement, Performance

Keywords:
defragmentation, read barrier, real-time scheduling, utilization