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https://issues.apache.org/jira/browse/MADLIB-1355?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Domino Valdano updated MADLIB-1355:
-----------------------------------
Fix Version/s: (was: v1.16)
v2.0
> Hide all global symbols in libmadlib.so by default
> --------------------------------------------------
>
> Key: MADLIB-1355
> URL: https://issues.apache.org/jira/browse/MADLIB-1355
> Project: Apache MADlib
> Issue Type: Task
> Components: All Modules
> Reporter: Domino Valdano
> Priority: Major
> Fix For: v2.0
>
>
> There was an intermittent crash in the deep_learning module due to both
> _tensorflow_ and _madlib_ using the same STL class (_std::set<string>_), and
> the functions in this class being publicly exported from _libmadlib.so_
> We fixed the crash by adding the symbols for the _std::set<string>_
> functions to the list of symbols the linker should hide during the build
> process. But we left a lot of other visible global symbols exported that
> shouldn't be exported... in order to be avoid extensive testing to make sure
> it doesn't break anything on an obscure platform or for some configurations.
> Without doing this, we will always run the risk that there is another library
> we are using (could be very indirect, such as with this case where python
> imports a module which then calls a C library) that conflicts with the
> version of STL or Boost that _madlib_ is using. If that happens, we could
> easily have another unexplained crash and it would be very difficult again to
> track down.
> The recommended best practice for exporting symbols from a shared object file
> is that we should hide everything by default, and only expose those functions
> which are officially a part of our API.
> We can hide everything by default by adding _-fvisibility=hidden_ to the list
> of default params to pass to the compiler in the master _CMakeLists.txt_.
> This will cause gcc to hide all symbols from external libraries by default.
> In addition, we should use either a #pragma or by adding a macro to prefix
> function definitions with that sets the visibility on specific functions we
> want to expose to default (visible). We can remove the
> _-unexported_symbols_list_ property from OSX and _--version-script_ property
> from other platforms, as these will no longer be needed. We should also
> delete the files they reference, _library.ver_ and
> _unexported_symbols_list.txt_
> Two good references on how to control visibility of symbols:
> [https://developer.apple.com/library/archive/technotes/tn2185/_index.html]
> [https://gcc.gnu.org/wiki/Visibility]
> Hopefully the list of symbols we need to expose is just the list of sql
> functions implemented in C, but there may be a few others that also need to
> be exposed.
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