node_load_markers

A single prestartup_script.py that wraps ComfyUI's custom node loader (nodes.load_custom_node) so the console clearly shows which node is currently loading — including a START/END marker around each node and a [node_name] tag on every line printed while that node loads. This makes it much easier to spot which custom node is slow, noisy, or crashing on startup.

The code in this package was written by Claude (Anthropic).

Why

By default, ComfyUI's startup log interleaves output from dozens of custom nodes with no clear boundaries, so a crash or a slow import is hard to attribute to a specific node. This script solves that without touching any of your existing custom node folders or their git repos.

Installation

1. Copy this whole folder, unchanged, into your ComfyUI custom_nodes directory:

   ComfyUI/custom_nodes/node_load_markers/
   ├── __init__.py
   └── prestartup_script.py
   

   or clone this in custom_nodes directory:

   git clone https://github.com/mykeehu/node_load_markers
   

2. Restart ComfyUI.

That's it — no further configuration. ComfyUI automatically runs every prestartup_script.py it finds in a direct subfolder of custom_nodes before it starts loading the actual custom nodes, which is what lets this script patch the loader in time.

The __init__.py is required too: ComfyUI also tries to import every subfolder of custom_nodes as a regular node package, and without an __init__.py that import fails with a FileNotFoundError. The one included here is intentionally empty (no NODE_CLASS_MAPPINGS) — it only exists to prevent that error.

What it does

Every custom node's loading is wrapped like this:

===== START: some_custom_node =====
[some_custom_node] ... anything that node itself prints ...
===== END: some_custom_node [OK, 0.42s] =====

On failure:

===== START: broken_node =====
[broken_node] ...
===== END: broken_node [EXCEPTION: <error message>, 0.10s] =====

Two refinements are built in:

• Line tagging. While a node is loading, its stdout/stderr output is wrapped so every line gets a [node_name] prefix. This keeps output attributed correctly even if the node's own logging is buffered or slightly delayed relative to a plain print().
• Deferred END marker. The END line for a node is not printed immediately — it's held back until either the next node's START is about to print, or ComfyUI is shutting down (via atexit). This keeps any trailing output that lands slightly after a node's own import call returns (e.g. from a background thread doing lazy initialization) visually inside that node's block instead of appearing to belong to the next one.

Known limitation

Because the END marker is deferred until the next node's START, the very last node loaded in a session will not show its END line during normal operation — it only gets flushed at process exit (which you typically won't see in the live console). This is a cosmetic trade-off, not a bug: everything up to the second-to-last node is fully bracketed.

Notes

• This does not modify any other custom node's files or git repo — they remain fully updatable via git/ComfyUI-Manager as normal.
• If a future ComfyUI version changes the signature of nodes.load_custom_node, only this one file needs adjusting.