Friday, October 17, 2025

Swift Profile Recorder

Johannes Weiss and Mitchell Allison (forum):

Swift Profile Recorder, an in-process sampling profiler for Swift services, is now available as an open source project.

[…]

Swift Profile Recorder enables you to:

  • Adopt profiling without extra privileges or system dependencies, allowing you to add profiling across a variety of compute environments with constrained permissions.
  • Collect samples using curl, allowing you to easily read profiler output via an HTTP endpoint without needing to learn specific tooling like perf, sample, DTrace, or eBPF (bpftrace).
  • Integrate with existing tools for visualization and analysis by supporting multiple industry-standard formats, including Linux perf script format, both the pprof file format as well as the /debug/pprof/profile endpoints, and also the collapsed format as used by the original FlameGraphs.

Apple has used Swift Profile Recorder at scale for several years as a tool for operating and debugging Swift services in production. Alongside the recent announcement of swift-parca, the Swift server ecosystem now has multiple profiling tools and approaches.

I’m intrigued by the idea of an app being able to profile itself.

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