Learn the Time to Learn: Replay Scheduling in Continual Learning

Marcus Klasson, Hedvig Kjellstrom, Cheng Zhang

Keywords: Continual Learning, Replay Methods, Reinforcement Learning

Abstract: Replay methods are known to be successful at mitigating catastrophic forgetting in continual learning scenarios despite having limited access to historical data. However, storing historical data is cheap in many real-world settings, yet replaying all historical data is often prohibited due to processing time constraints. In such settings, we propose that continual learning systems should learn the time to learn and schedule which tasks to replay at different time steps. We first demonstrate the benefits of our proposal by using Monte Carlo tree search to find a proper replay schedule, and show that the found replay schedules can outperform fixed scheduling policies when combined with multiple replay methods in various continual learning settings. Additionally, we propose a framework for learning replay scheduling policies with reinforcement learning. We show that the learned policies can generalize better in new continual learning scenarios compared to equally replaying all seen tasks, without added computational cost. Our study reveals the importance of learning the time to learn in continual learning, which brings current research closer to real-world needs.

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TL;DR: We demonstrate that scheduling which tasks to replay at different times is important in continual learning scenarios.

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