import #

Python 导入搜索顺序 #

当你启动 Python 时，它会构造一个列表 sys.path，按从左到右顺序查找模块/包：

脚本所在目录
1. 或空字符串 '' 代表“当前工作目录”
  1. 当你用 python -c “…” 执行命令时
  2. 或者用 python -m modulename 模块方式运行
  3. 或者在交互式解释器里直接执行时
PYTHONPATH 环境变量里声明的路径（如果有）
标准库路径
虚拟环境的 site-packages（…/.venv/lib/pythonX.Y/site-packages）

(vllm) root@lts-4090:/mnt/data1/yewang/study/vllm# cat test.py
import sys
print(sys.path)

(vllm) root@lts-4090:/mnt/data1/yewang/study/vllm# python test.py
['/mnt/data1/yewang/study/vllm', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python312.zip', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12/lib-dynload', '/mnt/data1/yewang/study/vllm/.venv/lib/python3.12/site-packages']
(vllm) root@lts-4090:/mnt/data1/yewang/study/vllm# cd ..
(vllm) root@lts-4090:/mnt/data1/yewang/study# python vllm/test.py
['/mnt/data1/yewang/study/vllm', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python312.zip', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12/lib-dynload', '/mnt/data1/yewang/study/vllm/.venv/lib/python3.12/site-packages']


(vllm) root@lts-4090:/mnt/data1/yewang/study/vllm# python -c "import sys; print(sys.path)"
['', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python312.zip', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12/lib-dynload', '/mnt/data1/yewang/study/vllm/.venv/lib/python3.12/site-packages']
(vllm) root@lts-4090:/mnt/data1/yewang/study/vllm# cd ..
(vllm) root@lts-4090:/mnt/data1/yewang/study# python -c "import sys; print(sys.path)"
['', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python312.zip', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12', '/root/.local/share/uv/python/cpython-3.12.9-linux-x86_64-gnu/lib/python3.12/lib-dynload', '/mnt/data1/yewang/study/vllm/.venv/lib/python3.12/site-packages']

python -c "import vllm; print(vllm.**file**)"
你在仓库根目录 /mnt/data1/yewang/study/vllm 下用 python -c … 测试时，sys.path[0] == ''（当前工作目录），第一个被查找的就是仓库根目录，这里恰好有个顶层目录 vllm/（源码包），于是就命中了源码版本，而不是 site-packages 里的已安装版本。
跑 examples/offline_inference/basic/basic.py 时，你又是在仓库里运行。多数情况下 sys.path[0] 会是脚本所在目录（…/examples/offline_inference/basic）。如果环境里 PYTHONPATH 含仓库根、或示例脚本/启动器做了路径注入（把仓库根加进 sys.path），仓库根就会进入前几位，仍然会先命中本地 vllm/。