Native App Performance (CLI-only)

xctrace

Quick start (CLI)

1. Record Time Profiler (attach):

# Start app yourself, then attach
xcrun xctrace record --template 'Time Profiler' --time-limit 90s --output /tmp/App.trace --attach <pid>

1. Record Time Profiler (launch):

xcrun xctrace record --template 'Time Profiler' --time-limit 90s --output /tmp/App.trace --launch -- /path/App.app/Contents/MacOS/App

1. Extract time samples:

scripts/extract_time_samples.py --trace /tmp/App.trace --output /tmp/time-sample.xml

1. Get load address for symbolication:

# While app is running
vmmap <pid> | rg -m1 "__TEXT" -n

1. Symbolicate + rank hotspots:

scripts/top_hotspots.py --samples /tmp/time-sample.xml \
  --binary /path/App.app/Contents/MacOS/App \
  --load-address 0x100000000 --top 30

Workflow notes

• Always confirm you’re profiling the correct binary (local build vs /Applications). Prefer direct binary path for

  --launch

  .
• Ensure you trigger the slow path during capture (menu open/close, refresh, etc.).
• If stacks are empty, capture longer or avoid idle sections.

• xcrun xctrace help record

  and

  xcrun xctrace help export

  show correct flags.

Included scripts

• scripts/record_time_profiler.sh

  : record via attach or launch.

• scripts/extract_time_samples.py

  : export time-sample XML from a trace.

• scripts/top_hotspots.py

  : symbolicate and rank top app frames.

Gotchas

• ASLR means you must use the runtime

  __TEXT

  load address from

  vmmap

  .
• If using a new build, update the

  --binary

  path; symbols must match the trace.
• CLI-only flow: no need to open Instruments if stacks are symbolicated via

  atos

  .