BatchIterator Store Probe

BatchIterator Store Probe (class BatchIteratorStoreProbe) is the debug window into the BatchIterator family's invisible state. The whole pack runs on Python dictionaries you can't see from the UI - iterator positions, collected strings, emitter counters - and when a loop misbehaves, this node is how you look at what's actually in there. When you fire it, it prints the value stored under a key_id in whichever of the three internal dicts you point it at, straight to the server console.

The painful part of debugging these stateful loop nodes is that nothing surfaces in the graph; the state lives in process memory and only the outputs you wire up show anything. StoreProbe is the pack's answer: put it in the branch that's misbehaving, tell it which dict and which key to inspect, trigger singal, and read the console line. It's the softer sibling of BatchIteratorErrorException - that one halts the run, this one just reports and keeps going.

How it works

It maintains a lookup of the three internal dicts under friendly names:

• multiline_text_iterator_count - the per-key_id positions of the multiline iterators
• storage_data_dict - the string-collection lists
• storage_data_counter - the emitter counters

When singal is true it looks up key_id in the selected dict and prints either the value or a "not a valid key in this dict" notice. singal false → nothing happens, and the node passes the signal through as void. It's an output node, so it sits at the end of a branch.

The inputs that matter

• key_id (STRING) - the key you want to inspect.
• target_dict - which dict to look in (the three choices above, default multiline_text_iterator_count).
• singal (BOOLEAN, default false) - the trigger; flip it true for one probe pass.

Installing it

No dependencies, no model files. ComfyUI Manager → search "AsyncOutput" → install and restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/teddy1565/ComfyUI-AsyncOutput

It's under AsyncOutput/BatchIterator/SystemTools.

Where people get burned

The output goes to the ComfyUI server console, not the node or a text widget - so if you're looking for the probe's result on the canvas, you're looking in the wrong place. Also, "not a valid key" and "empty" can look identical from the outside, so pair the probe with a check of whether the key ever got created (which itself tells you whether the Collection or Emitter actually ran). And keep in mind it only prints on the passes where singal is true - it's a probe, not a live dashboard.