Pain map
What breaks in document AI
290 production incidents from public threads. Every quote links to its source. Pick a category and check it yourself.
Many users at once on one GPU
18 of 18 quotes
“I am currently using llama.cpp, although I'm just now working on switching to vllm since it is better for concurrent inference, since it can interleave prompt-processing and decode.”
Hacker News · 21 October 2026 · open the thread “uploading a few image-heavy PDFs at once drives the server process to 100 % of its CPU limit and keeps it there.”
GitHub, open-webui · 21 October 2026 · in production · open the thread “Llama.cpp, fix the bugs that cause horrible speed decay in Qwen3.8-Flash-Next in longer context and with multiple users.”
Hacker News · 12 October 2026 · in production · open the thread “I think there could be an issue with KV cache I had with llama.cpp that randomly threw in characters from other thread's KV cache...”
Hacker News · 5 October 2026 · open the thread “in an environment with the ability to define multiple users, multiple API keys, it is not abnormal to have this type of situations.”
GitHub, anything-llm · 4 October 2026 · in production · open the thread Hit this one too? We are building for it. Join the waitlist.
“Three concurrent `POST /v1/chat/completions` requests for three different models on a cold router (no model loaded): one request succeeds, the other two fail immediately”
GitHub, llama.cpp · 11 September 2026 · open the thread “unlocked chat-blob read-modify-write silently drops messages under concurrency (chat_message table diverges from chat.chat)”
GitHub, open-webui · 18 August 2026 · in production · open the thread “I have experienced broken tool calling from VSCode to Qwen3-Coder-Next-80b-A3b and Qwen3.6-27b-MTP and I had a Hermes agent go haywire thanks to this issue. I just applied the patch referenced above and everything is rosy now!”
GitHub, llama.cpp · 23 July 2026 · open the thread “Under parallel mixed load (`-np 4 --kv-unified`), `llama-server` on an integrated HIP GPU (Strix Halo / gfx1151, 128 GB UMA) returns complete responses that verbatim belong to a different, earlier request.”
GitHub, llama.cpp · 22 July 2026 · open the thread “I've been fighting similar issues, but happens on `parallel=1` / `no-kv-unified=true` as well”
GitHub, llama.cpp · 22 July 2026 · open the thread “server -np 3 decode drops ~4.4x (166 -> 38 t/s) whenever the two busy slots are the non-contiguous pair {0,2}”
GitHub, llama.cpp · 17 July 2026 · open the thread “When testing qwen3.6:35b with OLLAMA_NUM_PARALLEL=3 configured, launching prompts via 3 separate CMD windows executes them strictly sequentially (one after another)”
GitHub, ollama · 18 June 2026 · in production · open the thread “I found that it's optimal to run 3 workers concurrently even though Ollama processes 1 request at a time.”
Hacker News · 13 June 2026 · open the thread “The ~25GB KV Cache is not released when a session ends or a "New Conversation" is triggered in the upstream app (Dify/RAGFlow).”
GitHub, ollama · 28 May 2026 · in production · open the thread “This is most visible on concurrent agent / RAG / chat workloads where two clients share the same system prompt + few-shot prefix but happen to land on different slots due to slot availability.”
GitHub, llama.cpp · 11 May 2026 · in production · open the thread “When 10 concurrent requests are made, 504 and 502 timeout errors occur.”
GitHub, ragflow · 27 March 2026 · open the thread “The V1 engine core silently deadlocks under concurrent load using default configuration.”
GitHub, vllm · 21 March 2026 · in production · open the thread “save embedding to vector DB freezes the whole application”
GitHub, open-webui · 24 November 2025 · open the thread Hit this one too? We are building for it. Join the waitlist.
Method
We collected 448 public posts published after 1 November 2025 in which a builder describes document AI failing. Each link was re-opened on 8 November 2026. We kept the 290 where the quote is on the page, the author describes an incident and not an opinion, and has no tie to a vendor. Quotes are verbatim and trimmed after 420 characters. The grouping is ours. A complaint is not a measurement.