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[Cherry-pick release/2.15] [xccl] WA: resolve libccl.so.1 next to the already loaded libccl.so.2 - #5676
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…#5670) #5648 preloaded libccl.so.1 by soname, assuming libtorch_xpu.so's RPATH would locate it the same way it locates libccl.so.2. It does not, so the workaround never took effect and PYTORCHDGQ-10126 still reproduces. LD_DEBUG on a PyPI/venv install shows only three RPATHs ever being used -- numpy's extension module, torch/_C.cpython-*.so and libtorch_global_deps.so -- all objects that were dlopen'd directly. libtorch_xpu.so is pulled in as an indirect dependency, so glibc resolves our dlopen() against those, never against ours. libccl.so.2 is found only because it is a DT_NEEDED of libtorch_global_deps.so: find library=libccl.so.2 ... (RPATH from file .../libtorch_global_deps.so) find library=libccl.so.1 ... search cache=/etc/ld.so.cache ... (system search path) Ask the loader for the resolved path of libccl.so.2 and open libccl.so.1 from the same directory instead, which does not depend on any search path. (cherry picked from commit d44bbbc)
This was referenced Oct 12, 2026
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#5648 preloaded libccl.so.1 by soname, assuming libtorch_xpu.so's RPATH would locate it the same way it locates libccl.so.2. It does not, so the workaround never took effect and PYTORCHDGQ-10126 still reproduces.
LD_DEBUG on a PyPI/venv install shows only three RPATHs ever being used -- numpy's extension module, torch/_C.cpython-*.so and libtorch_global_deps.so -- all objects that were dlopen'd directly. libtorch_xpu.so is pulled in as an indirect dependency, so glibc resolves our dlopen() against those, never against ours. libccl.so.2 is found only because it is a DT_NEEDED of libtorch_global_deps.so:
find library=libccl.so.2 ... (RPATH from file .../libtorch_global_deps.so)
find library=libccl.so.1 ... search cache=/etc/ld.so.cache
... (system search path)
Ask the loader for the resolved path of libccl.so.2 and open libccl.so.1 from the same directory instead, which does not depend on any search path.
Cherry-pick of #5670 to
release/2.15.Cherry-picked from commit d44bbbc.