Improving Scalability and Performance: DoorDash's Cache Rearchitecture

DoorDash, the leading food delivery platform, has recently implemented a major rearchitecture of its caching system to enhance scalability and performance. This initiative involved reevaluating and revamping the heterogeneous caching system that was being used across all of DoorDash's microservices. By introducing a common, multi-layered cache, DoorDash was able to address various challenges and achieve a more efficient and streamlined caching solution.

The Need for Rearchitecting the Cache

DoorDash faced several issues with its previous caching system, which was based on a fragmented approach. The adoption of a fragmented cache led to a lack of consistency and increased complexity in managing and maintaining the caching infrastructure. In order to overcome these challenges and further improve the platform's performance, DoorDash decided to rearchitect its cache to provide a unified and generic mechanism.

Achieving a Common, Multi-Layered Cache

The rearchitecture effort undertaken by DoorDash involved the implementation of a common, multi-layered cache system. This new cache system provides a centralized and standardized approach to caching across all microservices. By consolidating the caching logic into a common layer, DoorDash simplified the overall architecture and reduced the complexity associated with managing multiple caching systems.

The multi-layered cache architecture consists of different layers, each serving a specific purpose. The first layer, known as the distributed in-memory cache, is responsible for caching frequently accessed data at the node level. This layer ensures fast and efficient retrieval of data, reducing the need for repeated database queries and improving response times. The second layer, a shared memory cache, is designed to store relatively stable data that can be shared across multiple microservices. This layer eliminates the need for redundant caching and improves overall cache utilization.

Additionally, DoorDash introduced a third layer called the external storage cache. This layer is responsible for caching data that is expensive to compute or retrieve, such as database results or network calls. By caching this data in an external storage system, DoorDash minimizes the impact on the underlying microservices and significantly improves performance.

Benefits and Impact

DoorDash's cache rearchitecture has resulted in numerous benefits and positive outcomes. The adoption of a common, multi-layered cache has enhanced the scalability and performance of the platform in several ways:

1. Improved Response Times: The multi-layered cache system has significantly reduced the response times of DoorDash's microservices. By caching frequently accessed data and reducing the reliance on recurring database queries, DoorDash can deliver faster and more responsive experiences to its users.
2. Reduced Database Load: With the introduction of a distributed in-memory cache, DoorDash has been successful in offloading a substantial portion of the database load. This improvement has not only resulted in improved performance but has also relieved pressure from the database infrastructure, leading to a more scalable and efficient overall system.
3. Improved Cache Utilization: The consolidation of the caching logic into a common layer has allowed DoorDash to achieve better cache utilization. By eliminating redundant caching mechanisms and providing a standardized approach, DoorDash can efficiently utilize the cache capacity across all microservices.
4. Simplified Management and Maintenance: The rearchitected cache system has simplified the management and maintenance of the caching infrastructure. With a unified caching mechanism in place, DoorDash can easily monitor and troubleshoot any issues that arise, leading to faster resolution and improved overall system stability.

Conclusion

DoorDash's rearchitecture of its cache system has proven to be a pivotal move towards enhancing scalability and performance. By introducing a common, multi-layered cache, DoorDash has successfully addressed the challenges associated with a fragmented caching system and achieved a more efficient and streamlined caching solution. The benefits of this rearchitecture are evident in the improved response times, reduced database load, better cache utilization, and simplified management and maintenance. DoorDash's commitment to continuously improving its infrastructure demonstrates its dedication to delivering exceptional experiences to its users and ensuring the platform's long-term success.