Lily Li


Lily is a senior software developer. She became passionate about performance and scalability in networking and distributed systems when obtaining her Master’s Degree from University of Waterloo. For the last two years, she has been working in D2L focusing on scalability issues in AWS, building large-scale web applications based on Serverless technologies and event-driven architecture. She has also been leading on the effort of best practices and design patterns for microservices. As an advocate of software performance engineering, she enjoys to deliver talks on performance and scalability to her peers. Prior to D2L, Lily worked with large-scale messaging system in RIM.

When Serverless Gets In the Way of Scalability

In the age of countless cloud service offerings we often live in an idealized bubble where everything can auto-scale infinitely. In particular, serverless computing enables automatic fast provisioning/deprovisioning of server resources. However, scaling your compute power this quickly is not always beneficial and can even break your entire system. For example, storage systems may have fixed capacity; even with auto-scaling, the scaling takes longer time, resulting in unbalanced capacity between computing power and storage. This will make the storage systems the bottlenecks in the system. Therefore, a design without proper capacity management may lead to complete failure of the system under increasing load.

At D2L we have been developing microservices using serveless technologies. In this talk, you will learn: * the challenges we have faced in scaling serverless applications. We will demonstrate real-world examples. * various approaches we used to overcome the scalability challenges, including concurrency limit, backoff and retry and TCP-like congestion control. We will compare the pro. and cons. of each approach and give advice on best practices.