Integration Guide: Wiring HprofDumpDataSource into system_server

Files to modify in AOSP frameworks/base

1. Create the data source

Copy HprofDumpDataSource.java to:

services/core/java/com/android/server/am/HprofDumpDataSource.java

2. Register in ActivityManagerService

In ActivityManagerService.java, add to the constructor or systemReady():

// In ActivityManagerService.java, after other Perfetto data sources are initialized:
private HprofDumpDataSource mHprofDumpDataSource;

// In systemReady() or start():
mHprofDumpDataSource = new HprofDumpDataSource(this);

This is the same pattern as WindowTracingDataSource which is created in WindowManagerService and registers itself with Perfetto in its constructor.

3. SELinux policy (if needed)

The data source writes to /data/local/tmp/perfetto_hprof/. This directory must be writable by system_server. On userdebug/eng builds this should work. For production, a dedicated directory with proper SELinux labels may be needed.

4. Build file

Add HprofDumpDataSource.java to the appropriate Android.bp or Android.mk for the services module.

Trace config to test

adb shell perfetto -c - --txt <<EOF
buffers { size_kb: 262144 }
data_sources {
  config {
    name: "android.hprof_dump"
  }
}
duration_ms: 60000
EOF

Notes

• The data source uses the existing AMS.dumpHeap() API -- no new system APIs needed
• The dump is async: AMS sends a binder call to the target app, the app does the dump, then calls back
• Large hprof files (50-200MB) are split into 4MB chunks
• Bitmap PNGs are written as separate packets
• The data source cleans up temp files after writing to the trace