GCH: Hints for Triggering Garbage Collections

  • Authors:

  • Dries Buytaert;Kris Venstermans;Lieven Eeckhout;Koen Bosschere

  • Affiliations:

  • ELIS Department, Ghent University --- HiPEAC member, St.-Pietersnieuwstraat 41, B-9000 Gent, Belgium;ELIS Department, Ghent University --- HiPEAC member, St.-Pietersnieuwstraat 41, B-9000 Gent, Belgium;ELIS Department, Ghent University --- HiPEAC member, St.-Pietersnieuwstraat 41, B-9000 Gent, Belgium;ELIS Department, Ghent University --- HiPEAC member, St.-Pietersnieuwstraat 41, B-9000 Gent, Belgium

  • Venue:
  • Transactions on High-Performance Embedded Architectures and Compilers I
  • Year:
  • 2007

Quantified Score

Hi-index 0.00

Visualization

Abstract

This paper shows that Appel-style garbage collectors often make suboptimal decisions both in terms of whenand howto collect. We argue that garbage collection should be done when the amount of live bytes is low (in order to minimize the collection cost) and when the amount of dead objects is high (in order to maximize the available heap size after collection). In addition, we observe that Appel-style collectors sometimes trigger a nursery collection in cases where a full-heap collection would have been better.Based on these observations, we propose garbage collection hints (GCH)which is a profile-directed method for guiding garbage collection. Off-line profiling is used to identify favorable collection points in the program code. In those favorable collection points, the garbage collector dynamically chooses between nursery and full-heap collections based on an analytical garbage collector cost-benefit model. By doing so, GCH guides the collector in terms of whenand howto collect. Experimental results using the SPECjvm98 benchmarks and two generational garbage collectors show that substantial reductions can be obtained in garbage collection time (up to 29X) and that the overall execution time can be reduced by more than 10%. In addition, we also show that GCH reduces the maximum pause times and outperforms user-inserted forced garbage collections.