Undefined symbols to build or run Pytorch on macOS

[essandess]

Pytorch fails to compile on macOS because of the undefined symbol google::glog_internal_namespace_::IsGoogleLoggingInitialized():

:info:build Undefined symbols for architecture x86_64:
:info:build   "google::glog_internal_namespace_::IsGoogleLoggingInitialized()", referenced from:
:info:build       c10::InitCaffeLogging(int*, char**) in Logging.cpp.o
:info:build ld: symbol(s) not found for architecture x86_64
:info:build clang: error: linker command failed with exit code 1 (use -v to see invocation)

Related:

• Build fails with clang-cl due to undefined symbols #575
• https://trac.macports.org/ticket/62921

[sergiud]

Make sure to use search first. See #125.

[essandess]

Make sure to use search first. See #125.

I'm not familiar enough with the internals of glog or torch's dependence on glog to understand your response. How is this resolved? Are you saying it's an issue with torch? What's the specific resolution?

[sergiud]

There is nothing to resolve in glog. PyTorch uses an internal glog symbol which is not part of the API. The corresponding public API function was added to master only recently (#651).

[xkszltl]

I believe the issue may be much more wide-spread than you expected.

Although it's technically UB, I won't blame them for using it because it's the only way to reliably init glog for multiple libs.
It's essentially a large community effort patching glog bug that should be fixed long ago but not.

In glog 0.5.0, there's simply no way around, which can be a major issue for adoption.
Besides, recently I've seen many libs (both open-source and proprietary) hitting the issue on macOS (due the relatively aggressive upgrade of homebrew).

[sergiud]

The very first hit in your screenshot shows a clean way to test whether an initialization was performed which works irrespective of glog version. What's wrong with that?

[xkszltl]

That only works if you have full control of glog.
A common scenario is, 2 libs both use glog. They cannot tell whether glog is already initialized by anyone else. They cannot even "try-init" because that'll lead to a fatal error and kill the process:

glog/src/utilities.cc

Lines 337 to 338 in 0b3d4cb

	CHECK(!IsGoogleLoggingInitialized())
	<< "You called InitGoogleLogging() twice!";

[sergiud]

The described scenario doesn't seem to apply to PyTorch.

Regardless, I reject your idea of providing any kind of compatibility to internal symbols as I already made this very clear. The next version of glog will contain the necessary functionality.

I'm locking the discussion due to pointless arguing.