Idle unload never happens again if the client disconnects while a sleeping graph is waking up

[hansy2]

Describe the bug

With model groups and --idle_unload_timeout_seconds, a MediaPipe LLM graph is normally idle-unloaded after the timeout. If a client sends a request to a sleeping graph and disconnects while the graph is still waking up (reloading), the graph comes up as loaded but is never idle-unloaded again. Later normal requests don't fix this: the graph stays loaded until the server restarts.

With a 26B model this leaves ~16 GB of RAM allocated indefinitely. In our case it stayed loaded for ~4 hours with a 600 s timeout.

To Reproduce

Any small LLM works. The graph below is a standard HttpLLMCalculator graph with device: "GPU", max_num_seqs: 4, enable_prefix_caching: false, cache_size: 0.

config.json:

{"model_config_list":[{"config":{"name":"tiny","base_path":"/path/to/graph_dir","group_name":"g"}}]}

ovms --config_path config.json --rest_port 8011 --idle_unload_timeout_seconds 30 --metrics_enable

# graph starts SLEEPING; send a request and abort it during wake-up
timeout 0.5 curl -sN localhost:8011/v3/chat/completions -H 'Content-Type: application/json' \
  -d '{"model":"tiny","stream":true,"messages":[{"role":"user","content":"Hi"}],"max_tokens":10}'

# wait well beyond the timeout
sleep 90
curl -s localhost:8011/metrics | grep -E '^ovms_(graph_loaded|current_graphs|requests_accepted)'

Observed

• Log: triggering lazy wake-up reload -> RELOADING -> AVAILABLE -> wake-up completed. After that there is no Idle unloading model group line, ever.
• Metrics stay at ovms_graph_loaded{name="tiny"} 1, ovms_current_graphs{name="tiny"} 0, and all ovms_requests_accepted counters are 0 (the aborted request was never counted).
• Sending further normal requests afterwards and waiting beyond the timeout: still not unloaded.

Expected behavior

The graph is idle-unloaded after --idle_unload_timeout_seconds like after any other request. An aborted request during wake-up should not keep the group "in use".

Control cases (all unload correctly after the timeout)

• Normal unary request
• Streaming request aborted by the client mid-generation (graph already loaded)

My guess is that the request aborted during wake-up is never counted in ovms_requests_accepted / finished, so the group's in-use reference is never released. I haven't checked this in the code.

Configuration

• OVMS 2026.4.0.869b2186a (OpenVINO 2026.4.0-22959, GenAI 2026.4.0.0-3407), binary package for Ubuntu 24.04 running on Ubuntu 26.04
• Intel Core Ultra X7 358H (Panther Lake), Arc B390 iGPU (device: "GPU"), 64 GB RAM
• Models: gemma-4-26b-a4b-it-int4-ov (VLM continuous batching servable), reproduced with Qwen2.5-1.5B-Instruct-int4-ov

Workaround

An external watchdog reads /metrics and restarts the server if ovms_graph_loaded is 1, ovms_current_graphs is 0 and no ovms_requests_accepted counter has changed for 2× the idle timeout.

---