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Manuals / Playwright with Python / Chapter 30

Part 4 · Advanced Techniques · advanced · ~40 min · Chapter 30 of 61

22. Parallel Execution & Sharding

pytest-xdist for parallel runs pip install pytest-xdist pytest -n 4 # run using 4 parallel workers pytest -n auto # auto-detect CPU core count pytest -n <count> What it does: Distributes tests across multiple worker processes running in parallel instead of sequentially. Types/params: ● <count> (integer or "auto") — number of parallel workers; "auto" picks based on available CPU cores Pointers: Spe

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Overview

What it does: Distributes tests across multiple worker processes running in parallel instead of sequentially. Types/params: Pointers: Speed gains are significant but not linear — too many workers on too few CPU cores causes contention that can actually slow things down (ties into Chapter 32's performance tuning). Tests must be properly isolated (no shared mutable state, no fixed ports/files) or parallel execution surfaces race conditions that don't show up running sequentially.

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Chapter learning outcomes
  • Sharding tests across machines/CI runners

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22. Parallel Execution & Sharding deliverable

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