HSF Packaging Group Meeting #17, January 24, 2018

Introduction (Graeme Stewart)

Forward look at tasks for 2018
- Complete Use Cases Document. No aim of complete convergence between experiments, will note where there are differences in different areas of the community.
- Establish working version of proposed test stack, compare against use cases (~March time)
- Update Packaging Technical Note based on work since then (Use Cases, Portage, Test Stack)
- Release “(Test) Stack in Box” for CVMFS/Container deployment, could be used as a foundation for small experiments (Spring-Late Summer time)
2018 Events
- WLCG/HSF Workshop 26-29 March (Naples). Noted that early bird registration closes on Feb 16th. Wide agenda, inc. Software Development session, where packaging fits in.
- CHEP 2018, 9-13 July (Sofia). High level Packaging Abstract submitted. An abstract on Spack/SpackDev from FNAL has also been submitted.
News from HSF
- Community White Paper published (still open for signing)
- Note Software Development Chapter and dedicated paper from Software Development WG on ArXiv
Comments/Questions
- Ben has a usecase for Portage (tensorflow on CentOS 6) - will communicate with Guilherme and Graeme about this offline.

All CMSSW libs/exes built on SL7 with Spack
- Externals added as spack packages + scram xml for runtime paths (run/link)
- Many deps missing
- Scram sets up runtime
FWLite with Spack on MacOS
- Relocation (via install_name_tool) took long time
- PR to Spack to simplify run of tool
MacOS Build Distribution
- Distribute without rpath changes
- Allow non-admins to install a bundle via a disk image
- Use “sparse disk image” using hdiutil: a R/W image that grows/can be compacted as needed
- Very simple to setup!
Disk Image for FWlite/Fireworks
- Homebrew for clang/gfortran/cmake
- Spack to build FWlite etc
- Script/symlinks to bin/ path in disk images
Also: one with just Homebrew, one with gentoo prefix
- Some issues with these to resolve
Comments from Guilherme on Portage bootstrap
- Uses system compiler to bootstrap a compiler for the prefix - you can use a Mac build of gcc4.9 to get started (will then build gcc more easily)
- Bug reports are very welcome
Spack binary caches do work, with Partick’s patches
Spack have released 0.11 and plan a monthly release cycle from now on

Binary compatibility could save a lot of build time and space (more re-use)
- Raise topic to promote discussion and knowledge sharing
C++ ABI compatibility is a complex subject
- How package is written
- What compiler/standard is used
Topic of interest with broad discussion
- Marco: Compatibility between gcc6.X and gcc7.X should be assured (for all X)
- Marco: ROOT header compilation is very g++ dialect sensitive (11/14/17)
- Pere: STL classes do layout memory differently (in general) between dialects, so this is really a danger (hence the warnings)
- Marco: BOOST libraries also very dialect sensitive
- Consensus that C++ dialect should be consistent
- Chris: last few clang versions have had ‘fixes’ to name mangling, so were not fully backward compatible
- Marco: Clang and gcc mixing in LHCb did throw up some problems (e.g., std::map use caused segfaults)
- Marco: Needed new version of binutils to use avx2 instructions, but then linker incompatibilities were thrown up affecting static libraries built with the older linker
- Marco: Wanted to use some system libraries, like openssl, that get, e.g., security fixes; plugins would help if dependencies could be isolated
- Pere: be more explicit with dependencies