ci: sample runner memory pressure during iOS E2E (diagnostic)

.github/workflows/e2e-tests.yml

@@ -146,10 +146,10 @@ jobs:
           node-version: '24.10.0'
           cache: 'pnpm'
 
-      - name: Setup Xcode 26.4.1
+      - name: Setup Xcode 26.6
         uses: maxim-lobanov/setup-xcode@ed7a3b1fda3918c0306d1b724322adc0b8cc0a90 # v1.7.0
         with:
-          xcode-version: '26.4.1'
+          xcode-version: '26.6'
 
       - name: Install Watchman
         run: brew install watchman
@@ -200,6 +200,25 @@ jobs:
           path: ./apps/playground/ios/build/Build/Products/Debug-iphonesimulator/HarnessPlayground.app
           key: ios-app-playground
 
+      # Two backgrounded samplers (persist across later steps via nohup):
+      #  1. mem-pressure.log  - system swap/compressor/free every 2s (timeline)
+      #  2. mem-proc.log      - `top -l1 -o mem` every 10s: honest per-process
+      #     physical footprint (phys_footprint, no RSS shared-page double-count)
+      #     + a PhysMem total + process count. Ranks the real consumers.
+      # Goal: attribute the 7 GB / 3 vCPU pressure to specific processes and
+      # bring them down so Harness fits on the standard macos runner.
+      - name: Start memory-pressure sampler
+        shell: bash
+        run: |
+          SAMPLE_LOG="$RUNNER_TEMP/mem-pressure.log"
+          PROC_LOG="$RUNNER_TEMP/mem-proc.log"
+          nohup bash -c 'while true; do echo "=== $(date -u +%Y-%m-%dT%H:%M:%SZ) ==="; sysctl -n vm.swapusage; vm_stat; sleep 2; done' > "$SAMPLE_LOG" 2>&1 &
+          echo $! > "$RUNNER_TEMP/mem-sampler.pid"
+          nohup bash -c 'while true; do echo "=== $(date -u +%Y-%m-%dT%H:%M:%SZ) nprocs=$(ps -A | wc -l | tr -d " ") ==="; top -l 1 -o mem -n 45 -stats pid,mem,command; sleep 10; done' > "$PROC_LOG" 2>&1 &
+          echo $! > "$RUNNER_TEMP/mem-proc.pid"
+          echo "pressure sampler PID $(cat "$RUNNER_TEMP/mem-sampler.pid") -> $SAMPLE_LOG"
+          echo "process  sampler PID $(cat "$RUNNER_TEMP/mem-proc.pid") -> $PROC_LOG"
+
       - name: Run React Native Harness
         uses: ./
         with:
@@ -213,6 +232,65 @@ jobs:
             echo "HARNESS_RUNNER=$HARNESS_RUNNER"
             echo "HARNESS_EXIT_CODE=$HARNESS_EXIT_CODE"
 
+      - name: Stop sampler and summarize memory pressure
+        if: always()
+        shell: bash
+        run: |
+          PID="$(cat "$RUNNER_TEMP/mem-sampler.pid" 2>/dev/null || true)"
+          if [ -n "$PID" ]; then kill "$PID" 2>/dev/null || true; fi
+          PPID_="$(cat "$RUNNER_TEMP/mem-proc.pid" 2>/dev/null || true)"
+          if [ -n "$PPID_" ]; then kill "$PPID_" 2>/dev/null || true; fi
+          LOG="$RUNNER_TEMP/mem-pressure.log"
+          if [ ! -s "$LOG" ]; then echo "no sampler log found"; exit 0; fi
+
+          PAGE=16384
+          PEAK_SWAP_M="$(grep -o 'used = [0-9.]*M' "$LOG" | sed 's/used = //; s/M//' | sort -n | tail -1)"
+          PEAK_COMP_PAGES="$(grep 'occupied by compressor' "$LOG" | grep -oE '[0-9]+' | sort -n | tail -1)"
+          MIN_FREE_PAGES="$(grep 'Pages free' "$LOG" | grep -oE '[0-9]+' | sort -n | head -1)"
+          FIRST_SWAPOUT="$(grep 'Swapouts' "$LOG" | head -1 | grep -oE '[0-9]+' | head -1)"
+          LAST_SWAPOUT="$(grep 'Swapouts' "$LOG" | tail -1 | grep -oE '[0-9]+' | head -1)"
+          PEAK_SWAP_M="${PEAK_SWAP_M:-0}"; PEAK_COMP_PAGES="${PEAK_COMP_PAGES:-0}"
+          MIN_FREE_PAGES="${MIN_FREE_PAGES:-0}"; FIRST_SWAPOUT="${FIRST_SWAPOUT:-0}"; LAST_SWAPOUT="${LAST_SWAPOUT:-0}"
+          PEAK_COMP_MB=$(( PEAK_COMP_PAGES * PAGE / 1048576 ))
+          MIN_FREE_MB=$(( MIN_FREE_PAGES * PAGE / 1048576 ))
+          SWAPOUT_DELTA=$(( LAST_SWAPOUT - FIRST_SWAPOUT ))
+
+          {
+            echo "### iOS runner memory pressure"
+            echo ""
+            echo "- Peak swap used: **${PEAK_SWAP_M} MB**"
+            echo "- Peak compressed memory: **${PEAK_COMP_MB} MB** (${PEAK_COMP_PAGES} pages)"
+            echo "- Min free memory: **${MIN_FREE_MB} MB** (${MIN_FREE_PAGES} pages)"
+            echo "- Swapouts during run (delta): **${SWAPOUT_DELTA}**"
+            echo "- Runner: macos-latest (3 vCPU / 7 GB), page size ${PAGE} B"
+          } >> "$GITHUB_STEP_SUMMARY"
+
+          echo "peak_swap_mb=${PEAK_SWAP_M} peak_compressed_mb=${PEAK_COMP_MB} min_free_mb=${MIN_FREE_MB} swapout_delta=${SWAPOUT_DELTA}"
+
+          # Honest physical footprint: top's PhysMem line (no RSS shared-page
+          # double-count). Per-process MEM (phys_footprint) is in the artifact.
+          PROC_LOG="$RUNNER_TEMP/mem-proc.log"
+          if [ -s "$PROC_LOG" ]; then
+            PEAK_PHYS="$(grep -o 'PhysMem: [0-9]*[MG] used' "$PROC_LOG" | grep -oE '[0-9]+[MG]' | awk '/G$/{sub(/G/,"");print $1*1024;next}{sub(/M/,"");print}' | sort -n | tail -1)"
+            PEAK_NPROCS="$(grep -oE 'nprocs=[0-9]+' "$PROC_LOG" | grep -oE '[0-9]+' | sort -n | tail -1)"
+            {
+              echo "- Peak physical memory used (top PhysMem): **${PEAK_PHYS:-?} MB**"
+              echo "- Peak process count: **${PEAK_NPROCS:-?}**"
+              echo "- Per-process physical footprint (top MEM) in artifact \`mem-proc.log\`"
+            } >> "$GITHUB_STEP_SUMMARY"
+            echo "peak_phys_mb=${PEAK_PHYS:-0} peak_nprocs=${PEAK_NPROCS:-0}"
+          fi
+
+      - name: Upload memory samples
+        if: always()
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: mem-pressure-e2e-ios
+          path: |
+            ${{ runner.temp }}/mem-pressure.log
+            ${{ runner.temp }}/mem-proc.log
+          if-no-files-found: warn
+
       - name: Upload Harness logs
         if: always()
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2

.github/workflows/ios-simulator-startup-timings.yml

@@ -0,0 +1,170 @@
+name: Simulator boot benchmark
+
+on:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  simulator-boot:
+    strategy:
+      fail-fast: false
+      matrix:
+        runtime:
+          - iOS-26-2
+          - iOS-26-4
+          - iOS-26-5
+
+    runs-on: macos-26
+    timeout-minutes: 20
+
+    steps:
+      - name: Select Xcode 26.6
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          sudo xcode-select \
+            --switch /Applications/Xcode_26.6.app/Contents/Developer
+
+          xcodebuild -version
+
+          echo "SIMULATOR_CACHE_KEY=core-simulator-device-ios-26-5-xcode-26-6-${ImageOS}-${ImageVersion}" >> "$GITHUB_ENV"
+
+      - name: Restore iOS 26.5 simulator cache
+        id: cache-ios-26-5-restore
+        if: matrix.runtime == 'iOS-26-5'
+        uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: ~/Library/Developer/CoreSimulator/Devices/FD9EC0F9-63AA-4C2F-B0F5-224AAE68866E
+          key: ${{ env.SIMULATOR_CACHE_KEY }}
+
+      - name: Inspect available simulators
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          xcrun simctl list runtimes
+          xcrun simctl list devices available
+
+      - name: Measure existing simulator boot
+        shell: bash
+        env:
+          RUNTIME_SUFFIX: ${{ matrix.runtime }}
+          DEVICE_NAME: iPhone 17 Pro
+        run: |
+          set -euo pipefail
+
+          RUNTIME_ID="com.apple.CoreSimulator.SimRuntime.${RUNTIME_SUFFIX}"
+          BOOT_LOG="$RUNNER_TEMP/bootstatus-${RUNTIME_SUFFIX}.log"
+
+          echo "Looking for:"
+          echo "  Runtime: $RUNTIME_ID"
+          echo "  Device:  $DEVICE_NAME"
+
+          # Verify that the requested runtime is installed.
+          if ! xcrun simctl list runtimes -j |
+            jq -e --arg runtime "$RUNTIME_ID" '
+              .runtimes[]
+              | select(
+                  .identifier == $runtime
+                  and .isAvailable == true
+                )
+            ' >/dev/null; then
+            echo "::error::Runtime $RUNTIME_ID is not available"
+            exit 1
+          fi
+
+          # Select an existing available device only.
+          UDID="$(
+            xcrun simctl list devices available -j |
+              jq -er \
+                --arg runtime "$RUNTIME_ID" \
+                --arg name "$DEVICE_NAME" '
+                  .devices[$runtime]
+                  | map(
+                      select(
+                        .name == $name
+                        and .isAvailable == true
+                      )
+                    )
+                  | .[0].udid
+                '
+          )" || {
+            echo "::error::No existing $DEVICE_NAME found for $RUNTIME_ID"
+            echo "Available devices:"
+            xcrun simctl list devices available
+            exit 1
+          }
+
+          echo "Selected existing simulator:"
+          echo "  $DEVICE_NAME"
+          echo "  $RUNTIME_ID"
+          echo "  $UDID"
+
+          # Do not erase, recreate, or delete the selected device.
+          xcrun simctl shutdown "$UDID" 2>/dev/null || true
+
+          START_SECONDS="$(date +%s)"
+
+          echo "=== Boot request ==="
+          time xcrun simctl boot "$UDID"
+
+          echo "=== Boot completion ==="
+          set +e
+          xcrun simctl bootstatus "$UDID" -b 2>&1 |
+            tee "$BOOT_LOG"
+          BOOT_STATUS="${PIPESTATUS[0]}"
+          set -e
+
+          END_SECONDS="$(date +%s)"
+          ELAPSED_SECONDS="$((END_SECONDS - START_SECONDS))"
+
+          MIGRATION_SAMPLES="$(
+            grep -c "Waiting on Data Migration" "$BOOT_LOG" || true
+          )"
+
+          {
+            echo "### Existing simulator boot result"
+            echo
+            echo "- Runtime: \`$RUNTIME_ID\`"
+            echo "- Device: \`$DEVICE_NAME\`"
+            echo "- UDID: \`$UDID\`"
+            echo "- Duration: **${ELAPSED_SECONDS}s**"
+            echo "- Migration samples: **${MIGRATION_SAMPLES}**"
+            echo "- Runner image: \`${ImageOS:-unknown}\`"
+            echo "- Image version: \`${ImageVersion:-unknown}\`"
+          } >> "$GITHUB_STEP_SUMMARY"
+
+          if [[ "$BOOT_STATUS" -ne 0 ]]; then
+            echo "::error::Simulator failed to finish booting"
+            exit "$BOOT_STATUS"
+          fi
+
+      - name: Shut down iOS 26.5 simulator before caching
+        id: shutdown-ios-26-5
+        if: always() && matrix.runtime == 'iOS-26-5'
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          UDID="FD9EC0F9-63AA-4C2F-B0F5-224AAE68866E"
+          xcrun simctl shutdown "$UDID" || true
+
+          for _ in {1..30}; do
+            if xcrun simctl list devices | grep -F "$UDID" | grep -q '(Shutdown)'; then
+              exit 0
+            fi
+            sleep 1
+          done
+
+          echo "::error::Simulator $UDID did not shut down before caching"
+          exit 1
+
+      - name: Save iOS 26.5 simulator cache
+        if: always() && matrix.runtime == 'iOS-26-5' && steps.shutdown-ios-26-5.outcome == 'success' && steps.cache-ios-26-5-restore.outputs.cache-hit != 'true'
+        uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: ~/Library/Developer/CoreSimulator/Devices/FD9EC0F9-63AA-4C2F-B0F5-224AAE68866E
+          key: ${{ steps.cache-ios-26-5-restore.outputs.cache-primary-key }}