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Running Apache Spark experiments in my sleep (and on a plane)

Running Apache Spark experiments in my sleep (and on a plane)

Data Netflix Tech Blog
Netflix reduced Apache Spark tuning latency by building a parallel loop that runs production-scale experiments to isolate memory and shuffle bottlenecks.
What: Netflix engineers accelerated pipeline optimization for their member-sessionizer by running multiple test workloads concurrently, rather than sequential tuning runs, to rapidly identify performance regressions.
Why it matters: This shift in experimentation methodology reflects the growing necessity of treating infrastructure testing as a continuous, parallelized loop, especially when scaling data pipelines to handle tens of billions of events.
Deep dive
  • Netflix's member-sessionizer pipeline processes tens of billions of hourly client events.
  • Traditional serial tuning of Spark jobs is prohibitively slow due to scale.
  • The team implemented a framework to launch multiple production-scale tests in parallel.
  • This allows for direct comparison of memory usage and shuffle performance across different configurations.
  • Parallel experimentation significantly reduces the time required to diagnose bottlenecks.
  • This approach enables rapid iterative improvement rather than static, infrequent tuning cycles.
Original article

Netflix's member-sessionizer pipeline turns tens of billions of hourly client events into viewing sessions, but scale bottlenecks made ordinary tuning painfully slow. Instead of optimizing one Spark run at a time, the team built a parallel experiment loop that launched, monitored, and compared multiple production-scale tests to expose memory and shuffle bottlenecks faster.

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