Performance Testing Serverside Applications

Performance testing server-side applications is a crucial process to help understand how the application behaves under load. It helps software teams fine-tune their applications to get the best performance while keeping the infrastructure costs low. Performance testing answers several important questions such as:

Leaky Pipe How much load can your application sustain before it buckles under?

A lesson I learned recently is that performance testing should not be an after-thought. Software teams should start performance testing early in the release cycle and not wait until the end to do it. I once worked on a team that built a backend service that passed all unit, integration and end-to-end tests with flying colors. QA engineers didn’t find any bugs in the application’s logic. However, the performance was just terrible when we ran load tests on it. On a single m4.large instance, the application supported 80% fewer requests than the team had estimated! The main bottleneck was found to be the 2-core CPU that was utilized to its maximum capacity as the application issued several queries to the database and applied complex algorithms to build a graph. Investigations by developers revealed that to reduce the amount of work the CPU was doing, it would require significant design changes. But it was already too late - the deadline was just weeks away. We decided to proceed with the release - albeit by over-provisioning the hardware and over-running our cost estimates by a factor of 3. All this could have been avoided if we had done performance testing sooner.

Performance testing is a broad topic. Teams I work with run load and soak tests to measure performance metrics such as throughput, latency, resource utilization, etc. using a wide variety of tools. At Glu, we build REST services in Java and use the following tools for our performance tests:

Before I wrap this post up, there are few other important lessons I’d like to share:

I hope this post was helpful. Would love to hear your thoughts, the tools and the approach you take for performance testing. Till next time.

This article was written by Umer Mansoor. Please leave your comments below and like on Facebook or follow on Twitter to stay up-to-date.

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