Troubleshooting

Matthijs Douze edited this page Oct 3, 2018 · 19 revisions

We receive bug reports related to the GPU code that are not actionable because impossible to reproduce. If you start a bug report, please make sure to include (use a gist if it is too bulky):

  • version of OS, type of GPU, nvidia-smi output

  • output of ldd on executable or _swigfaiss_gpu.so for the Python version

  • a gdb stacktrace

  • please open a new issue unless you are certain that you have the exact same one as an existing one. This makes it easier for us to triage.

  • if you post code, please make it self-contained and as short as possible

Also, please consider the following notes on how to productively report bugs.

Python errors

ImportError: No module named swigfaiss

This means that Faiss was not compiled.

SWIG error

cd ../python; swig -Doverride= -python -c++ -DGPU_WRAPPER -o ../python/swigfaiss_gpu_wrap.cxx ../swigfaiss.swig
../gpu/StandardGpuResources.h:67: Error: Syntax error in input(3).
make: *** [../python/swigfaiss_gpu_wrap.cxx] error 1

This is probably because the swig version is too old (swig 2.0 does not parse C++11 >>), and you may have erased the swig-generated files by doing make clean. You can restore them by

cd ../python
git checkout swigfaiss_gpu_wrap.cxx swigfaiss_gpu.py swigfaiss_wrap.cxx swigfaiss.py

Then make py again.

NULL/nullptr/0

C++ has changed several times how NULL pointers should be represented. In the C++ source, we use nullptr. This is recognized by C++11 compliant compilers. If your flavor of C++ has another idea about this, pass option -Dnullptr=NULL to the compiler.

GPU Precomputed table error

If you get the following assertion error when constructing an GpuIndexIVFPQ with precomputed tables:

Faiss assertion usePrecomputed_ || IVFPQ::isSupportedNoPrecomputedSubDimSize( this->d / subQuantizers_) failed in void faiss::gpu::GpuIndexIVFPQ::assertSettings_() const at GpuIndexIVFPQ.cu:469Aborted (core dumped)

Then make sure that the ratio between the dimension and the PQ size (d/M) is one of the values mentioned in this function:

https://rawgit.com/facebookresearch/faiss/master/docs/html/PQScanMultiPassNoPrecomputed_8cu_source.html#l00029

If this is not the case, you can pre-process the input vectors with an OPQ transform.

undefined reference to operator new[]

Here you have probably erased the Faiss Makefile or forgotten to copy the makefile.inc as instructed in the INSTALL file.

What happens is that make is using a C compiler (cc) to compile C++.

Compile command without options

If you see

make
g++ -o tests/test_blas tests/test_blas.cpp

Then something happened with the Makefile. You may have overwritten it with makefile.inc for example.

Slow brute-force search with OpenBLAS

The search performance with OpenBLAS can degrade seriously because of a bad interaction between OpenMP and OpenBLAS threads. To avoid this, export OMP_WAIT_POLICY=PASSIVE before running the executable. See issue #53

Crashes in pure Python code

This has been fixed in version 1.4.0, that introduced automatic tracking of c++ references in Python. If you see this error in a version >=1.4.0, please report it as an issue.

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