Serverless Performance with Headless Chrome

The number of people running interesting binaries in AWS Lambda is increasing, and with the recent release of Headless Chromium—a version of the Chrome browser that can run without a UI—there have been experiments and different open-source projects of individuals running it inside an AWS Lambda environment. Running a large, memory-intensive piece of software designed for desktops inside a serverless function presents interesting performance challenges, including how to minimize cold start time and how to optimize the right amount of memory for the function.

This talk is about optimizing performance of chromium inside Lambda using multiple data sources, including AWS X-Ray traces and custom metrics. While the talk is focused on headless chrome in AWS Lambda, the performance techniques can be applied to any memory or compute-intensive serverless functions.

Transcript

1. SERVERLESS PERFORMANCE LESSONS WITH HEADLESS CHOME @smithclay ServerlessConf NY, Oct 2017
2. SERVERLESS PERF STRATEGY ƛ ƛ is it fast? ƛ ƛ is it fast concurrently? ƛ ƛ what's the worst case? why?
3. AWS Lambda Function index.handler (node.js runtime) ./bin/chromedriver process.exec https://medium.com/clog/running-selenium-and-headless-chrome-on-aws-lambda-fb350458e4df ./bin/headless_chrome BIG BROWSER, LITTLE FUNCTION + Simple Selenium Script
4. AWS LAMBDA: BATTERIES INCLUDED DATA SOURCES Amazon Cloudwatch Logs Amazon Cloudwatch Metrics AWS X-Ray Traces
5. DISTRIBUTED TRACE VISUALIZTION 1200ms 400ms 370ms Service A Service B Service C Time
6. HELLO, COLD START AWS X-Ray Trace: AWS Function invoked from the Developer Console
7. COLD VS WARM START Notice: Function gets called almost immediately after the service receives the trigger.
8. COLD STARTS: MORE ANALYSIS NEEDED Aggregate function latencies from X-Ray to understand trends
9. VISUALIATING TRACES IN AGGREGATE 1) How long does it take for my function to initialize? 2) Where is time generally being spent?
10. FOR THIS FUNCTION, COLD STARTS ARE RARE Over a 24 hour period, the function rarely experiences cold starts.
11. AWS LAMBDA: COMMON SETTINGS TO MODIFY Language Runtime "Memory" Dropdown Function size (mb)
12. DURATION: BEFORE AND AFTER INCREASING MEMORY 768mb 1152mb Chromium needed more memory!
13. WRAP UP • Collect data for several days for many function runs. • Consider enabling x-ray traces for non-trivial functions • Test scenarios where your function has many concurrent executions (i.e. large spike in the number of requests) • Don't be afraid to increase memory: it might end up costing less. •Measure and share!
14. THANKS! slides: @smithclay + speakerdeck.com Original blog post: https://blog.newrelic.com/2017/06/20/lambda- functions-xray-traces-custom-serverless-metrics/