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Disable abi3 for free-threaded python #2034

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Disable abi3 for free-threaded python #2034

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12 changes: 9 additions & 3 deletions hopper/setup.py
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,12 @@
DISABLE_HDIMDIFF64 = os.getenv("FLASH_ATTENTION_DISABLE_HDIMDIFF64", "FALSE") == "TRUE"
DISABLE_HDIMDIFF192 = os.getenv("FLASH_ATTENTION_DISABLE_HDIMDIFF192", "FALSE") == "TRUE"

# Auto-disable the Python limited API (abi3) for free-threaded Python (3.13t+)
# Free-threaded Python does not support the limited API
# See: https://docs.python.org/3/howto/free-threading-extensions.html
FREE_THREADED = sysconfig.get_config_var("Py_GIL_DISABLED")
DISABLE_ABI3 = FREE_THREADED or os.getenv("FLASH_ATTENTION_DISABLE_ABI3", "FALSE") == "TRUE"
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@rgommers rgommers Jan 2, 2026

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Adding the extra environment variable here is potentially useful, but not related to free-threading support. I'd personally not include it unless a maintainer asks for it.


# HACK: we monkey patch pytorch's _write_ninja_file to pass
# "-gencode arch=compute_sm90a,code=sm_90a" to files ending in '_sm90.cu',
# and pass "-gencode arch=compute_sm80,code=sm_80" to files ending in '_sm80.cu'
Expand Down Expand Up @@ -585,11 +591,11 @@ def nvcc_threads_args():
name=f"{PACKAGE_NAME}._C",
sources=sources,
extra_compile_args={
"cxx": ["-O3", "-std=c++17", "-DPy_LIMITED_API=0x03090000"] + stable_args + feature_args,
"cxx": ["-O3", "-std=c++17"] + ([] if DISABLE_ABI3 else ["-DPy_LIMITED_API=0x03090000"]) + stable_args + feature_args,
"nvcc": nvcc_threads_args() + nvcc_flags + cc_flag + feature_args,
},
include_dirs=include_dirs,
py_limited_api=True,
py_limited_api=not DISABLE_ABI3,
)
)

Expand Down Expand Up @@ -698,5 +704,5 @@ def run(self):
"packaging",
"ninja",
],
options={"bdist_wheel": {"py_limited_api": "cp39"}},
options={} if DISABLE_ABI3 else {"bdist_wheel": {"py_limited_api": "cp39"}},
)