Module perfetto 

Perfetto sink that writes trace events directly to .pftrace files on disk.

This provides an alternative to Scuba-based tracing that:

• Has no row limits (vs 400K Scuba limit)
• Has no ingestion latency (immediate file writes)
• Uses native Perfetto protobuf format (no conversion needed)
• Supports distributed file systems like OILFS

Directory Layout

{trace_dir}/
├── executions/
│   ├── {execution_id}/
│   │   ├── {process_name}.pftrace
│   │   └── ...
│   └── latest -> {execution_id}/   # symlink to most recent

Default Trace Directory

If not specified, traces are written to /tmp/{username}/monarch_traces/

Structs

PerfettoFileSink

File-based Perfetto sink that writes .pftrace files.

Enums

PerfettoTraceMode

Controls what events are captured in Perfetto traces.

Constants

MONARCH_TRACE_DIR_ENV

Environment variable to override the default trace directory.

USER_TELEMETRY_PREFIX

The target prefix for user-facing telemetry spans.

Statics

PERFETTO_TRACE_MODE

Perfetto trace mode controlling which events are captured. Valid values: “off”, “user” (default), “dev”

Functions

default_trace_dir

Returns the default trace directory.