Protected heap sharing for memory-constrained java environments

ABSTRACT

Multitasking is one of capabilities we often want to have in memory-constrained embedded systems. To support multiple address spaces within a small physical memory, a simple memory management frequently encounters the lack of available memory. Our paper presents an efficient heap memory management scheme that reduces memory footprints by adaptively sharing heaps among multiple tasks in JVM environments. We modified KVM from Sun Microsystems so that Java applications acquire or release heaps in a shared pool on an as-needed basis. To protect address spaces among tasks in the absence of virtual memory capabilities, we use memory protection units (MPUs) by incorporating them into our heap sharing scheme. Our experiments with J2ME MIDP applications show significant reductions by 33% on average, ranging from 6% to 50% in memory usage over the execution. The overheads of our scheme in garbage collection are kept low. The execution times in our scheme increase only by 0.2% on average.

REFERENCES

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INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.3 Language Constructs and Features
          Subjects: Dynamic storage management

Additional Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.4 Processors
          Subjects: Memory management (garbage collection)
  D.4 OPERATING SYSTEMS
      D.4.2 Storage Management
          Subjects: Allocation/deallocation strategies; Virtual memory; Garbage collection

General Terms:
Design, Performance

Keywords:
dynamic memory management, garbage collection, heap sharing, memory protection unit