MDC+: A Cooperative Approach to Memory-Efficient Fork-Based Checkpointing for In-Memory Database Systems

Consistent checkpointing is a critical for in-memory databases (IMDBs) but its resource-intensive nature poses challenges for small- and medium-sized deployments in cloud environments, where memory utilization directly affects operational costs. Although traditional fork-based checkpointing offers merits in terms of performance and implementation simplicity, it incurs a considerable rise in memory footprint during checkpointing, particularly under update-intensive workloads. Memory provisioning emerges as a practical remedy to handle peak demands without compromising performance, albeit with potential concerns related to memory over-provisioning. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In this article, we propose MDC+, a memory-efficient fork-based checkpointing scheme designed to maintain a reasonable memory footprint during checkpointing by leveraging collaboration among an IMDB, a user-level memory allocator, and the operating system. We explore two key techniques within the checkpointing scheme: (1) memory dump-based checkpointing, which enables early memory release, and (2) hint-based segregated memory allocation, which isolates immutable and updatable data to minimize page duplication. Our evaluation demonstrates that MDC+ significantly lowers peak memory footprint during checkpointing without affecting throughput or checkpointing time.