sPHENIX discussion of software

[pinkenburg <pinkenburg AT bnl.gov>]

Hi folks,

as announced yesterday - we will switch to root6 as default today. That 
means the "new" build will point to our libraries which were compiled 
against root6. If you just source the sphenix_setup.csh (or *.sh for 
sphenix accounts) script you will work with root6.

root5 builds are still compiled daily, they are available when sourcing 
the setup script with root5 as argument:

source /opt/sphenix/core/bin/sphenix_setup.csh -n root5
source /opt/sphenix/core/bin/sphenix_setup.sh -n root5 for sphenix accounts.

One caveat: root6 needs the path to include files. This is done by 
setting the ROOT_INCLUDE_PATH environment variable. This is done by the 
setup script which sets it to our installation area. If you work with 
privately compiled libraries you will need to add to this include path 
(prepending it so root looks in your area first). If you follow our 
advice how to build packages into a common install area:

mkdir <buildarea>
cd <buildarea>
<packagedir>/autogen.sh --prefix=<installarea>
make install

the include files are installed in <installarea>/include. If you use 
this scheme we have a script which sets up your ROOT_INCLUDE_PATH 
properly by

source /opt/sphenix/core/bin/setup_root6.csh <installarea>
(use /opt/sphenix/core/bin/setup_root6.sh for sphenix accounts)

There is still some quirkiness in this, sometimes root6 needs the 
package-wise subdirectories (where we install the include files) of the 
include area. This script adds all your subdirectories as well and 
appends the proper include directories from our build to the 
ROOT_INCLUDE_PATH. If you install a new package you have to re-source 
the script to add your new subdirectory.

I set up a wiki page (linked to the bottom of our software page under 
special topics):

https://wiki.bnl.gov/sPHENIX/index.php/Sphenix_root6

It repeats the above and shows how you need to modify the configure.ac 
and Makefile.am of your package to compile with root6 while keeping 
backward compatibility with root5

Let's see how this goes - what can possibly go wrong?
Chris

P.S. I've been running with root6 for weeks now and would say that our 
libraries and Fun4All_G4_*.C macros  work just fine. But I expect there 
will be issues in user macros (cling is based on a compiler, means it 
has rules while CINT is basically winging it allowing many bad things in 
macros). cling is very talkative on errors and you normally only get the 
first one before it goes on its rant (which often makes the original 
error scroll off the screen even with 1000 line backing store). Pipe the 
output into a file (root.exe -q -b MyMacro.C >& error.log) and look at 
the first few lines, it's normally just a missing include file or library

P.P.S. In terms of results - our default Fun4All_G4_*.C macros produce 
identical results under root5 and root6 (last digit diffs in genfit 
because the new root6 based version uses eigen instead of root for its math)

--
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Christopher H. Pinkenburg       ;    pinkenburg AT bnl.gov
                                ;    http://www.phenix.bnl.gov/~pinkenbu

Brookhaven National Laboratory  ;    phone: (631) 344-5692
Physics Department Bldg 510 C   ;    fax:   (631) 344-3253
Upton, NY 11973-5000

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