[Halld-offline] Offline Software Meeting Minutes, March 18, 2015

[Mark Ito]

Folks,

Find the minutes below and at

https://halldweb.jlab.org/wiki/index.php/GlueX_Offline_Meeting,_March_18,_2015#Minutes

   -- Mark
________________________________________

GlueX Offline Meeting, March 18, 2015, Minutes

Present:

  * *CMU*: Curtis Meyer
  * *JLab*: Alex Barnes, Mark Ito (chair), David Lawrence, Paul
    Mattione, Kei Moriya, Eric Pooser, Mike Staib, Justin Stevens
  * *NU*: Sean Dobbs


Announcements

  * At JLab, the quota on /group/halld was raised from 300 GB to 400 GB.
  * Paul Mattione has checked in changes to the Analysis Library to add
    support for histograms and custom ROOT branches. See his email
    <https://mailman.jlab.org/pipermail/halld-offline/2015-March/001986.html>
    for details.
  * Mark packaged a new release of sim-recon, version 1.0.0. See his
    email
    <https://mailman.jlab.org/pipermail/halld-offline/2015-March/001988.html>
    for details. We discussed the new version numbering scheme. Not
    everyone loves it, but there were no strong objections.


Review of Minutes from March 4

We looked at the minutes 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Offline_Meeting,_March_4,_2015#Minutes>. 


Intel Code Validation Tools

We briefly discussed access to the Intel code validation tools discussed 
last time. At present they are not available for general use at JLab, 
though that may change. Mike Staib has been using an educational 
version, Paul Mattione is working on a 30-day free trial.

Commissioning-Branch-to-Trunk Migration

The copy of the commissioning branch of sim-recon on to the trunk was 
done Friday, March 6 
<https://mailman.jlab.org/pipermail/halld-offline/2015-March/001984.html>. 
Mark reported that he and Simon had some problems doing a 
best-practices-type merge of the branch to the trunk. It was unclear how 
to resolve all of the resulting conflicts. Instead the trunk was deleted 
and the branch copied to the trunk location. History on the branch was 
preserved, including history from before the branch. So far, no problems 
with this procedure have been reported.

Offline Monitoring Report

Kei reported that there have been a number of issues delaying the launch.

  * We upgraded to a new version of ROOT to fix memory leaks in the FFT
    package that we never call.
  * Paul and Nathan Sparks worked on a bug fix that caused crashes at
    the exit of hd_root jobs when certain combinations of plug-ins are
    run. They traced it to some global STL containers in one of the
    static libraries.
  * The current set of code is crashing for reasons to be investigated.


Summary of meeting with SciComp

Last week SciComp called a meeting to discuss new features with us. In 
attendance were Mark, David, Kei, Justin, and Paul.

 1. Chris Larrieu gave a presentation/demo of SWIF
    <https://halldweb.jlab.org/wiki/images/e/e7/Swif.pdf>. We plan to
    adopt the farm handling scripts we have been using for data
    challenges and offline monitoring to take advantage of this system,
    though work in that direction has not started yet.
 2. Ying Chen showed slide on the new Write-Through Cache
    <https://halldweb.jlab.org/wiki/images/8/84/Halld-WDM.pptx>. Files
    written to the this disk will be archived to tape after two weeks.
    When space gets short, files that have been archived will be deleted
    to make space for new files. There is a minimum size requirement of
    3 MB for a file to be archived. 20 TB of space on this device is now
    available to us.


GlueX Use of C++11 features and GCC Versions

Dmitry had privately discussed with Mark the idea of using C++11 
features in our offline code. We have not explicitly endorsed or 
prohibited such use, but Mark thought we should discuss it. He showed a 
table of GCC compilers 
<https://halldweb.jlab.org/wiki/index.php/GCC_at_JLab,_March_2015> used 
on systems around the Lab. If possible, it looks for now that we do not 
want to use any language features that are not available in the 4.4 
series compiler. Dmitry was particularly interested in using 
[http://en.wikipedia.org/wiki/Smart_pointer#shared_ptr_and_weak_ptr%7Cshared 
pointers. He claims that they are available in 4.4.

The GCC page on these features <https://gcc.gnu.org/projects/cxx0x.html> 
raises some flags, notably

1. "experimental/" in GCC, i. e., no guarantee that all behavior of 
these features preserved in future versions./
2. possibility of the need for special compiler flags to access these 
features.
Concern was raised by these items. We did not have an expert on hand.

One approach would be to simply wait until all of our commonly used 
systems catch up to, say, version 4.8 or greater. The only problem with 
that is that it might be a long time coming and meanwhile we lose the 
benefit of the new features which are standard for a lot of developers 
outside of GlueX.

David suggested that Dmitry try some of the features he is interested 
and see if behavior is different when using a 4.4 compiler versus a 4.8 
or 4.9 compiler. That would help us decide how to proceed.

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