cyclic dependencies

[nschloe]

albanyLib uses symbols from albanySTK (e.g., Albany::STKDiscretization::getOwnedDOF) which in turn uses symbols from albanyLib (e.g., createEpetraCommFromTeuchosComm). There's probably more.
How to best get this straight?

[ambrad]

Hi Nico,

That's a big can of worms. Albany has a lot of circular dependencies. We
put the lib listing on the link line three times (though two ought to do
it) to resolve these.

May I ask why you're looking into these issues?

Cheers,
Andrew

On Fri, Apr 10, 2015 at 3:35 PM, Nico Schlömer notifications@github.com
wrote:

albanyLib uses symbols from albanySTK (e.g.,
Albany::STKDiscretization::getOwnedDOF) which in turn uses symbols from
albanyLib (e.g., createEpetraCommFromTeuchosComm). There's probably more.
How to best get this straight?

—
Reply to this email directly or view it on GitHub
https://github.com/gahansen/Albany/issues/3.

[nschloe]

@ambrad I submitted a PR for TriBits (TriBITSPub/TriBITS#60) that changes Trilinos' exported CMake configuration files. To assert that the change doesn't break anything, @bartlettroscoe asked me to verify this against Albany builds. To make sure that all symbols are still defined, I enabled builds with -Wl,--no-undefined which brought this up.

[ambrad]

Hi Nico,

Would it be enough to build with a basic but full configuration of Albany?
Something like this I think would be comprehensive:

cmake -DALBANY_TRILINOS_DIR:PATH=/path/to/trilinos/install
-DENABLE_LCM:BOOL=ON -DENABLE_HYDRIDE:BOOL=ON -DENABLE_FELIX:BOOL=ON
-DENABLE_AERAS:BOOL=ON -DENABLE_QCAD:BOOL=ON -DENABLE_MOR:BOOL=ON
-DENABLE_ATO:BOOL=ON -DENABLE_SEE:BOOL=ON -DENABLE_AMP:BOOL=ON ..

Cheers,
Andrew

On Sat, Apr 11, 2015 at 1:45 PM, Nico Schlömer notifications@github.com
wrote:

@ambrad https://github.com/ambrad I submitted a PR for TriBits (
TriBITSPub/TriBITS#60 TriBITSPub/TriBITS#60)
that changes Trilinos' exported CMake configuration files. To assert that
the change doesn't break anything, @bartlettroscoe
https://github.com/bartlettroscoe asked me to verify this against
Albany builds. To make sure that all symbols are still defined, I enabled
builds with -Wl,--no-undefined which brought this up.

—
Reply to this email directly or view it on GitHub
https://github.com/gahansen/Albany/issues/3#issuecomment-91915121.

[nschloe]

Would it be enough to build with a basic but full configuration of Albany?

A standard build results in missing symbols from STK, for example, e.g.,

[...]
[ 96%] Built target albanySTKRebalance
Linking CXX executable Albany
[...]
disc/stk/libalbanySTK.so: undefined reference to `Ioss::Region::get_element_blocks() const'

Indeed, libalbanySTK is underlinked since it requires symbols from Trilinos::STK, but doesn't link against them. To fix this, I had added -Wl,--no-undefined which then showed those other errors.

[nschloe]

I managed to compile Albany now, but these dependency loops should still be fixed.

If libAlbany and libAlbanySTK mutually depend on each other such that you can't use one without the other, one may ask why they are separated into two different libraries in the first place. One relatively easy to implement fix for this is to just all all sources to libAlbany.

[gahansen]

Hi Nico,

Is this a remaining issue, or can I close this one too?

Glen

[bartlettroscoe]

Why does Albany ha e circular dependencies?

[bartlettroscoe]

How do you do shared pin builds?

[agsalin]

There was a point a few years ago where Glen discovered that dumping all Albany source into a single library caused an error that was fixed when braking it into multiple libraries. This occurred when he upgraded to a newer gcc (4.7 perhaps). We then broke albany into pieces based on directories (also projects), like libLCM and libQCAD, which led to circular dependencies. We fixed that by adding the libraries multiple times on the link line.

Since this has not caused problems, we haven't seen the need to fix it. Is there a reason to?

[bartlettroscoe]

Why not just make Albany one big library since that is what it is anyway if you have circular dependencies? Then you can use shared libs.

[agsalin]

Albany works fine with shared builds, as far as I know. I think the opposite behaviors is true: that shared libs allow you to get away with circular dependencies without repeating them on the link line.

I'm not sure if we would have the same problem that Glen saw before, like there was a limit of how many *.o's could be linked in a single library and we were exceeding it.

Anyway, I'm curious if there is any harm in what we are doing currently.

[gahansen]

I don't recall the version of gcc - back at about 4.7 several users encountered a linking error with debug builds. I don't recall if it was a file size issue or a number of symbols issue, but we resolved it at the time by breaking the single library into multiple. The original reason for doing this probably no longer valid, but I don't know if anyone has looked at it again since then.

[bartlettroscoe]

Can't do circular shared libs

https://cmake.org/cmake/help/v3.3/command/target_link_libraries.html

[bartlettroscoe]

Nico,

I don't think we need to force Albany to clean this up (it is not really any of our business). We just need to add a configure-time option for the TriBITS/Trilinos build to disable -Wl,--no-undefined when Albany developers need to build/install Trilinos to use with Albany. It is just that the default development build of Trilinos will have this turned on by default.