Experience Replay Optimization via ESMM for Stable Deep Reinforcement Learning

The memorization and reuse of experience, popularly known as experience replay (ER), has improved the performance of off-policy deep reinforcement learning (DRL) algorithms such as deep Q-networks (DQN) and deep deterministic policy gradients (DDPG). Despite its success, ER faces the challenges of noisy transitions, large memory sizes, and unstable returns. Researchers have introduced replay mechanisms focusing on experience selection strategies to address these issues. However, the choice of experience retention strategy has a significant influence on the selection strategy. Experience Replay Optimization (ERO) is a novel reinforcement learning algorithm that uses a deep replay policy for experience selection. However, ERO relies on the naive first-in-first-out (FIFO) retention strategy, which seeks to manage replay memory by constantly retaining recent experiences irrespective of their relevance to the agent's learning. FIFO sequentially overwrites the oldest experience with a new one when the replay memory is full. To improve the retention strategy of ERO, we propose an experience replay optimization with enhanced sequential memory management (ERO-ESMM). ERO-ESMM uses an improved sequential retention strategy to manage the replay memory efficiently and stabilize the performance of the DRL agent. The efficacy of the ESMM strategy is evaluated together with five additional retention strategies across four distinct OpenAI environments. The experimental results indicate that ESMM performs better than the other five fundamental retention strategies.