[bug]: reproducible nodes engine soft lock with collect/iterate nodes

[psychedelicious]

Is there an existing issue for this?

• I have searched the existing issues

OS

Linux

GPU

cuda

VRAM

24GB

What version did you experience this issue on?

feat/ui/nodes-api

What happened?

When using collection/iterate nodes incorrectly - two times in a row - it is possible to soft lock the nodes engine. The API still responds but it does not generate until restarting.

This is the error (no error is emitted via events):

{'type': 'int_collection', 'collection': [1826701614]}
Exception in thread invoker_processor:
Traceback (most recent call last):
  File "/usr/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/home/bat/Documents/Code/InvokeAI/invokeai/app/services/processor.py", line 123, in __process
    self.__invoker.invoke(graph_execution_state, invoke_all=True)
  File "/home/bat/Documents/Code/InvokeAI/invokeai/app/services/invoker.py", line 28, in invoke
    invocation = graph_execution_state.next()
  File "/home/bat/Documents/Code/InvokeAI/invokeai/app/services/graph.py", line 817, in next
    prepared_id = self._prepare()
  File "/home/bat/Documents/Code/InvokeAI/invokeai/app/services/graph.py", line 1026, in _prepare
    create_results = self._create_execution_node(next_node_id, iteration_mappings)  # type: ignore
  File "/home/bat/Documents/Code/InvokeAI/invokeai/app/services/graph.py", line 876, in _create_execution_node
    input_collection_edge = next(
StopIteration

To reproduce, connect a range output to the index input of an iterate node, invoke all, then make a new session and do it again. The above error is output each time, but it's only on the second invoke all that the engine stops executing.

Example malformed graph_execution_state (use the simple source graph to reproduce - run the graph twice, changing its ID between runs):

{
  "id": "9d060c16-e8c3-4817-9ec7-17e47b423ae9",
  "graph": {
    "id": "e4bf01c2-10ce-4b93-b247-ac7d0016c59b",
    "nodes": {
      "f4372771-1866-4119-929a-b735478e54f1": {
        "id": "f4372771-1866-4119-929a-b735478e54f1",
        "type": "random_range",
        "low": 0,
        "high": 2147483647,
        "size": 1,
        "seed": 0
      },
      "955935df-ee3c-4cdc-befd-7985f9f83347": {
        "id": "955935df-ee3c-4cdc-befd-7985f9f83347",
        "type": "iterate",
        "collection": [],
        "index": 0
      }
    },
    "edges": [
      {
        "source": {
          "node_id": "f4372771-1866-4119-929a-b735478e54f1",
          "field": "collection"
        },
        "destination": {
          "node_id": "955935df-ee3c-4cdc-befd-7985f9f83347",
          "field": "index"
        }
      }
    ]
  },
  "execution_graph": {
    "id": "3ce1b403-2506-419c-9ee1-28a4524bd95b",
    "nodes": {
      "b332dc93-3a72-4994-80fd-208cec63be28": {
        "id": "b332dc93-3a72-4994-80fd-208cec63be28",
        "type": "random_range",
        "low": 0,
        "high": 2147483647,
        "size": 1,
        "seed": 0
      }
    },
    "edges": []
  },
  "executed": [
    "f4372771-1866-4119-929a-b735478e54f1",
    "b332dc93-3a72-4994-80fd-208cec63be28"
  ],
  "executed_history": ["f4372771-1866-4119-929a-b735478e54f1"],
  "results": {
    "b332dc93-3a72-4994-80fd-208cec63be28": {
      "type": "int_collection",
      "collection": [1826701614]
    }
  },
  "errors": {},
  "prepared_source_mapping": {
    "b332dc93-3a72-4994-80fd-208cec63be28": "f4372771-1866-4119-929a-b735478e54f1"
  },
  "source_prepared_mapping": {
    "f4372771-1866-4119-929a-b735478e54f1": [
      "b332dc93-3a72-4994-80fd-208cec63be28"
    ]
  }
}

Screenshots

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Additional context

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Contact Details

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[Kyle0654]

Ah, you should never be connecting anything to the index input on an iterate node. That will be automatically filled in by the engine. I guess the docs on that aren't super clear. Is there a way to produce this aside from connecting to the index input on iterate nodes?

[psychedelicious]

Not aware of any other way to cause the issue - I did it on accident.

I can remove the index input from the UI so it is impossible to get into this situation from there, but this could allow a kind of denial-of-service attack, so it needs to be handled.