build(before-code-freeze): Export the stub's dynamic symbols when libpython is static - #451
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The manylinux base container builds CPython with --disable-shared, so on that platform triton_python_backend_stub links libpython3.x.a and the Py_* symbols live in the executable rather than a shared library. Python C extension modules are dlopen'ed and deliberately leave Py_* undefined -- every one of the 77 lib-dynload modules in the image does, math.so alone with 63 undefined symbols and no libpython in DT_NEEDED -- so they can only bind against the stub's dynamic symbol table. Without the export the stub links and starts, then fails on the first `import math`. Set ENABLE_EXPORTS, which makes CMake add the platform's flag (-Wl,--export-dynamic on Linux, per Platform/Linux.cmake), matching how CPython links its own interpreter. Gate it on the resolved library being an archive rather than on the platform. A shared libpython needs no export, so the Debian build is unaffected, and the condition stays correct if a target moves between the two linkage modes. The condition reads PYTHON_LIBRARY, not PYTHON_LIBRARIES: pybind11 arrives through FetchContent_MakeAvailable, which uses add_subdirectory, so only the cache entry find_library creates crosses back into this scope. PYTHON_LIBRARIES is a plain variable in pybind11's directory and is empty here, which would have made this a silent no-op.
The comment said RHEL_BUILD existed because pybind would otherwise pick up Python 3.6 in the RHEL base container, so PYBIND11_PYTHON_VERSION was set to force 3.12. That pin has been dropped from build.py -- pybind11 prefers the newest entry of its own Python_ADDITIONAL_VERSIONS list, and the manylinux base container puts a single interpreter first on PATH. RHEL_BUILD itself stays: it still selects the stub's link settings further down. Only the justification was wrong.
This was referenced Aug 5, 2026
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Greptile SummaryUpdates the stub link configuration so executables embedding a static libpython export their dynamic symbols, allowing Python extension modules to resolve
Confidence Score: 5/5The PR appears safe to merge. No blocking failure remains. Important Files Changed
Reviews (2): Last reviewed commit: "docs: Correct the stale RHEL_BUILD ratio..." | Re-trigger Greptile |
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August 5, 2026 23:31
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What does the PR do?
Set
ENABLE_EXPORTSontriton-python-backend-stubwhen libpython resolves to astatic archive. The manylinux base builds CPython
--disable-shared, so thePy_*symbols live in the stub executable; the 77lib-dynload/*.somodules linkno libpython and carry undefined
Py_*(mathalone: 63), so without the exportthe stub links and starts, then fails on the first
import math.Checklist
<commit_type>: <Title>Commit Type:
Related PRs:
Where should the reviewer start?
The
if(PYTHON_LIBRARY MATCHES "\\.a$")block inCMakeLists.txt.Test plan:
Covered by the internal RHEL/manylinux pipeline for the 26.08 upstream bump.
Caveats:
Gated on the resolved library being an archive, not on the platform, so the Debian
build (shared libpython) is unaffected. Uses
PYTHON_LIBRARY, notPYTHON_LIBRARIES: pybind11 arrives viaFetchContent_MakeAvailable, which usesadd_subdirectory, so only thefind_librarycache entry crosses into this scope.Background
Part of the 26.08 "build against latest upstream container" work: the base image
moved to
cuda:13.4-devel-manylinux--26.08, which changed the default GCCtoolset, the Python layout and the bundled OpenSSL.
Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)
- Resolves: TRI-1650
CI (internal): [#61271932](http://tritonserver.local/ci/pipelines/61271932)