[Python][Packaging] Strip unnecessary symbols from libarrow.so to reduce wheel package size

[raulcd]

Describe the enhancement requested

There has been some effort in order to reduce pyarrow size and there are some issues opened in order to split pyarrow wheels in order to have pyarrow-core, pyarrow-all, etcetera.

There seems to be the possibility to strip unnecessary symbols via strip --discard-all. The libarrow.so file seems to be reduced from 61MB to 45 MB.

Another example:

-rwxrwxr-x 1 user group  49M Feb 22 18:55 libarrow.so.1600.0.0

$ strip --strip-unneeded libarrow.so.1600.0.0

-rwxrwxr-x 1 user group  33M Mar 12 15:27 libarrow.so.1600.0.0

This issue is to investigate the possibility of using strip and the possible disadvantages.

edited to fix typo

Component(s)

Packaging, Python

[kou]

Can we check whether backtrace on crash is still available with strip --discard-all/--strip-unneeded? (We may need to use gdb for it.)

[jorisvandenbossche]

Potentially related issue with some useful content (but specifically for the wheels, so maybe mostly relevant for our cython code?): pypa/cibuildwheel#331

That issue mentions numpy used --strip-all though multibuild, although nowadays the wheel building infrastructure is different (using cibuildwheel), and I don't directly see any mention of that in the numpy sources.
Pandas is using -Wl,--strip-all: pandas: https://github.com/pandas-dev/pandas/blob/8da8b54412020a9478d7b6b0fccde9f9bbf3d8ba/pyproject.toml#L151

[pitrou]

I've tried on the reproducer in #38770 and only --strip-debug preserves the full backtrace including non-public functions:

[...]
#7  0x00007ffff310b277 in std::terminate() () from /lib/x86_64-linux-gnu/libstdc++.so.6
#8  0x00007ffff310b4d8 in __cxa_throw () from /lib/x86_64-linux-gnu/libstdc++.so.6
#9  0x00007ffff373737b in std::__throw_bad_variant_access(char const*) () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
#10 0x00007ffff3737399 in std::__throw_bad_variant_access(bool) () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
#11 0x00007ffff37960e7 in arrow::compute::internal::(anonymous namespace)::FilterMetaFunction::ExecuteImpl(std::vector<arrow::Datum, std::allocator<arrow::Datum> > const&, arrow::compute::FunctionOptions const*, arrow::compute::ExecContext*) const [clone .cold] ()
   from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
#12 0x00007ffff42cc3e0 in arrow::compute::MetaFunction::Execute(std::vector<arrow::Datum, std::allocator<arrow::Datum> > const&, arrow::compute::FunctionOptions const*, arrow::compute::ExecContext*) const () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
[...]

More powerful strip options make the backtrace less useful because the symbols of non-public functions are removed:

[...]
#7  0x00007ffff310b277 in std::terminate() () from /lib/x86_64-linux-gnu/libstdc++.so.6
#8  0x00007ffff310b4d8 in __cxa_throw () from /lib/x86_64-linux-gnu/libstdc++.so.6
#9  0x00007ffff373737b in ?? () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
#10 0x00007ffff3737399 in ?? () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
#11 0x00007ffff37960e7 in ?? () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
#12 0x00007ffff42cc3e0 in arrow::compute::MetaFunction::Execute(std::vector<arrow::Datum, std::allocator<arrow::Datum> > const&, arrow::compute::FunctionOptions const*, arrow::compute::ExecContext*) const () from /home/antoine/t/venv-3.10/lib/python3.10/site-packages/pyarrow/libarrow.so.1500
[...]

This is on the PyArrow 15.0.2 wheels. The savings are still significant: from 61MB (original) to 54MB (stripped) for libarrow.so.

[paleolimbot]

For pyarrow, there are also nightly wheel builds as well, correct? Might it also be an option to keep the debug symbols in those (so that there is a route to getting a user-reported stack trace) but strip them from the wheel most users get with a default pip?

[pitrou]

A user-reported stack trace would be possible with --strip-debug.

[raulcd]

For macOS on pandas it seems that -g0 was used:

• ENH: strip debug symbols from macOS wheels pandas-dev/pandas#51900

And the fix

• BLD: Try g0 on macos? pandas-dev/pandas#51971

[raulcd]

Issue resolved by pull request 42028
#42028