Scheduling real-time garbage collection on uniprocessors

Abstract

Managed languages such as Java and C# are increasingly being considered for hard real-time applications because of their productivity and software engineering advantages. Automatic memory management, or garbage collection, is a key enabler for robust, reusable libraries, yet remains a challenge for analysis and implementation of real-time execution environments. This paper comprehensively compares leading approaches to hard real-time garbage collection. There are many design decisions involved in selecting a real-time garbage collection algorithm. For time-based garbage collectors on uni-processors one must choose whether to use periodic, slack-based or hybrid scheduling. A significant impediment to valid experimental comparison of such choices is that commercial implementations use completely different proprietary infrastructures. We present Minuteman, a framework for experimenting with real-time collection algorithms in the context of a high-performance execution environment for real-time Java. We provide the first comparison of the approaches, both experimentally using realistic workloads, and analytically in terms of schedulability.

Idle time garbage collection scheduling

“…Such a system was first implemented in Metronome-TS [2] and showed significant improvement over the regular Metronome system. Kalibera et al [24] discuss different approaches to garbage collection scheduling on uniprocessor systems and classifies them in three categories: slack-based [21], periodic [3,4], and hybrid [2]. The authors compare performance and schedulability tests of different implementations of these systems, where the garbage collector is run on a separate thread to take advantage of the operating system scheduler.…”

Unix Philosophy and the Real World: Control Software for Humanoid Robots

“…Collection cycles introduce pause times that are unacceptable for real-time performance on humanoid robots (Johnson et al, 2015). Research on real-time garbage collection is ongoing (Yuasa, 1990;Bacon et al, 2003;Kalibera et al, 2011), while (Smith et al, 2014) use Java for real-time control by disabling garbage collection in the real-time module. If we can constrain the ordering of allocations and frees, then the situation improves.…”

Idle-Time Garbage-Collection Scheduling

“…A comprehensive overview of garbage collectors taking advantage of idle times is available in a previous article. 4 The authors classify different approaches in three categories: slack-based systems where the garbage collector is run when no other task in the system is active; periodic systems where the garbage collector is run at predefined time intervals for a given duration; and hybrid systems taking advantage of both ideas. The authors found that, on average, hybrid systems provide the best performance, but some applications favor a slack-based or periodic system.…”