ListView ANR during dynamic-height recycling on Android 10+

Profiling ListView ANRs from dynamic row heights on Android 10+

The most likely explanation is that Ti.UI.SIZE forces a full onMeasure/onLayout pass for every row during binding. With 500+ variably sized rows, scrolling multiplies these native measure passes on the main thread, triggering ANRs. This is the established pattern for Titanium Android ListViews with dynamic heights.

Likely explanation: Dynamic-height templates defeat view-holder recycling because each bind requires a fresh measurement. No single JS‑only tool can isolate this; the Android Studio CPU profiler (or Perfetto/systrace) on the main thread is the primary device for separating native layout time from V8 execution time.

Confirmed facts from the research brief: Ti.UI.SIZE row heights force a measure pass per row as data binds, multiplying onMeasure/onLayout work. Android Studio CPU profiler (or Perfetto/systrace) shows whether samples cluster in measure/layout versus V8/JS. Fixed row heights (dp values) typically eliminate or drastically reduce the ANR without data-model changes. Ti.API.info timestamps in postlayout handlers are a low-cost complement: log per‑row bind duration and count events per scroll to spot recycling failure.

Assumption: This diagnosis attributes the ANR to main‑thread measure/layout pressure from dynamic row heights; the V8 9.4 JIT heuristic change is speculative and requires CPU profiler verification.

1. Run the app on an Android 10+ device or emulator.
2. Open Android Studio, start a CPU Profiler session, select the main‑thread Java/Compositor trace, and reproduce the ANR‑triggering scroll. Check where samples concentrate: onMeasure, onLayout, or V8/JS functions.
3. Simultaneously, add temporary Ti.API.info logs inside the template's postlayout event to record timestamps and row indices. Count how many events fire during a single scroll gesture.
4. Switch all list‑item templates to fixed dp heights (e.g., height: 80dp). Replay the same scroll. If the ANR disappears, the dynamic‑height measure hypothesis is confirmed.
5. Use the Layout Inspector on a running debug build to observe whether row views are reused or freshly inflated during scrolling. Repeated inflation instead of reuse signals recycling defeat.

If the ANR persists after fixing row heights, consider whether the ListView uses a native Android RecyclerView wrapper or a pure Titanium JS implementation, as SDK version and binding architecture affect which profiler signals appear.