Hacktoberfest 2026：维护者为十月标记出来的 issue，仍然开放、适合新手。 浏览 Hacktoberfest issue

flm serve: streaming /api/chat segfaults the server on every request (insert() twice, generate() never called)

未关闭 适合新手
  • 哪里不对？
#757 0 条评论 0 个 reaction 已指派 0 人 在 GitHub 查看

维护者通常 4 天内回复

还没有人认领这个 Issue。

评估

难度
2/5
预计耗时
1-3 小时
新手友好度
78/100
Issue 类型
缺陷
描述清晰度
描述清楚
活跃度
活跃
技术栈
cpp
领域
api, backend

调研方向

从 src/server/rest_handler.cpp 中 792-823 行附近的 streaming /api/chat 分支开始，然后将其与 690-697 行附近的 streaming /api/generate 代码块进行比较。使用 issue 中针对 llama3.2:1b 和 gemma4-it:e4b 的 curl 请求，检查 streaming 是否保持活动状态、返回 token chunks 和一个带 stats 的 done chunk、与非 streaming 文本匹配，并执行一次 prefill。

由索引模型根据 Issue 内容生成。

描述

What happens

Every POST /api/chat with "stream": true crashes flm serve with SIGSEGV. The client gets no bytes back, and every other client loses the server too.

flm serve llama3.2:1b
curl -sN http://127.0.0.1:52625/api/chat -H 'Content-Type: application/json' \
  -d '{"model":"llama3.2:1b","messages":[{"role":"user","content":"Count from 1 to 5."}],"stream":true}'
# connection closes with no response; the flm process has exited (SIGSEGV)

It reproduces on llama3.2:1b and gemma4-it:e4b. The server log shows one Prefill chunk 1/1 line, then nothing. Backtraces from the core dumps:

llama3.2:1b                                  gemma4-it:e4b
#0 Sampler::sample_greedy(buffer<bf16>&)     #0 Sampler::sample_greedy(buffer<bf16>&)
#1 AutoModel::_shared_insert(...)            #1 AutoModel::_shared_insert(...)
#2 Llama3::insert(...)                       #2 Gemma4e::insert(...)
#3 RestHandler::handle_chat(...)             #3 RestHandler::handle_chat(...)
Cause

The streaming branch of handle_chat runs the insert() try block twice (rest_handler.cpp:792-819). It never calls generate() before ostream.finalize_chat() (:823).

The first insert() writes the whole prompt to token_history. The second one then prefix-matches all of it in AutoModel::_shared_insert (automodel.cpp:184-201). It erases every token, prefills an empty vector, and samples an empty logits buffer (:234).

This looks like the same code as #436, which reported empty chunks on v0.9.36 and was closed because the Ollama API is no longer maintained. On v1.0.6 the result is no longer an empty stream: the whole process crashes, including for clients that only use /v1/*. If the Ollama routes are staying unmaintained, removing /api/chat would also close this.

Fix we are carrying

Replace the second insert() block with the generate() block that streaming /api/generate already uses (:690-697):
https://github.com/noamsto/nix-amd-ai/blob/46d7a73c1044435cec0ff08410e1a3bc87cbc544/pkgs/fastflowlm/patches/stream-chat-generate.patch

The diff is small. Our copy of the file carries other patches, so the context lines differ from upstream's. With the fix, both models stream token chunks and then one done: true chunk with stats. The streamed text is byte-identical to the non-streaming reply, and there is one prefill per request. I can send this as a PR against main if that's useful.

Probes and logs: https://github.com/noamsto/nix-amd-ai/blob/46d7a73c1044435cec0ff08410e1a3bc87cbc544/bench-logs/oflm-api-conformance-2026-09-28-after-187/README.md

Environment

FLM v1.0.6 built from the tag, with our downstream request-handling patches applied. In this block those patches change only the bodies of the catch clauses. The double insert() and the missing generate() are upstream code.
Ryzen AI MAX+ 395 (Strix Halo), XDNA2 NPU, 8 columns. NixOS, Linux 7.2.8, amdxdna 0.10, NPU FW 1.1.2.65.

主要语言
C++
星标
1.9k
派生
158
平均合并
4 天 16 小时
30 天内合并 PR
14

环境准备

  • 提供 Dockerfile 或 Docker Compose 文件
  • 没有 Pull Request 模板
  • 阅读贡献指南

从这里开始

  1. 先读完整个 Issue，再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库，在一个分支上完成修改。
  4. 提交 Pull Request，并在描述里引用这个 Issue 编号。

ROCm/FastFlowLM 的其他 Issue

查看 ROCm/FastFlowLM 的全部 Issue

相似的 Issue

更多 C++ Issue

把新 issue 发到你的邮箱

精选适合新手参与的 GitHub issue 摘要。