[Halld-offline] Software Meeting Minutes, October 25, 2021

Mark Ito marki at jlab.org
Mon Oct 25 21:04:08 EDT 2021


Please find the minutes here 
and below.

   -- Mark


    GlueX Software Meeting, October 25, 2021, Minutes

Present: Alex Austregesilo, Thomas Britton, Sean Dobbs, Mark Ito 
(chair), Igal Jaegle, Richard Jones, David Lawrence, Simon Taylor, Beni 

There is a recording of this meeting 
<https://bluejeans.com/s/NkHJt0V1qUu/>. Log into the BlueJeans site 
<https://jlab.bluejeans.com> first to gain access (use your JLab 


 1. Power off of scosg16
    scosg16.jlab.org is going away. It will be replaced by
    scosg20.jlab.org as our OSG submit node.
      * scosg20 is two-factored. Use your JLab two-factor login method
        (i.e., the same as you use to log into hallgw.jlab.org, e.g.,
        MobilePASS) to login in.
      * scosg20 is not a GLOBUS endpoint, as scosg16 was. Use a Data
        Transfer Node (DTN) instead. Ask the computer center for access
        if you do not have it already.
 2. Compute Farm Updates
    Nodes on the JLab farm will transitioning from CentOS 7.7 to 7.9
    over the next months. As announced last week
    CentOS 7.9 nodes with be assigned the BMS_OSNAME corresponding to
    7.7 for the time being.
 3. *CentOS Stream 8*. Richard alerted us to the news that CERN and
    Fermilab are heading in the direction of CentOS Stream 8 as the next
    generation scientific computing platform. From slides shown at a
    CERN IT Technical-Users Meeting
    <https://halldweb.jlab.org/talks/2021/20211018-itum34.pdf>: "Going
    forward, we propose to target CentOS Stream 8 as the standard
    distribution for experiments."
      * David expressed the concern that with CentOS Stream streaming
        ahead, there might be OS-dependent gotcha's not captured by our
        versioning scheme. Richard proposed containers as a way around
        that. He also mentioned that the CERN/Fermi folks have
        operational experience with Stream without major difficulties,
        evidence of the lack of gotcha's.
      * David endorsed the idea of running in containers on the JLab
        farm. He pointed out that we already run containerized on all of
        the off-site platforms we use. Richard remarked that an added
        benefit of standardizing on containers is that non-JLab folks
        (e.g., Richard) could reproduce the OS exactly when
        troubleshooting reported problems, and not have to log into JLab
        to get the right OS.

      Review of Minutes from the Last Software Meeting

We went over the minutes from the meeting on October 11th 

        Doxygen and Documentation

Beni had been exploring the features of Doxygen by adding comments to 
the TOF and start counter code. He thinks there is a lot of promise in 
using Doxygen, but needs to learn the system a bit more before rendering 
judgment. He will give us a summary of what he has learned once he is 
farther along.

Richard brought up the use of Doxygen at an EIC simulation meeting with 
Makoto Asai in attendance. The feeling of the participants was that a 
PDF note was the best choice for the primary documentation vehicle. 
Doxygen was useful, but mainly to a small core of developers. This 
despite Geant4 having extensive Doxygen-oriented comments.

Having a summary of purpose and methods at the top of source files, 
using Doxygen syntax seems to be a consensus best practice.

        DL1MCTrigger Crashes With mysql rcdb/ccdb

We had more discussion of halld_recon Issue #81 

  * Alex had posted an example that will produce the error reliably.
    Interestingly, it only occurs for SQLite CCDB files on a raw data
    file. The original post reported the bug in simulation, and only
    when using a MySQL server for CCDB. Alex example only has trouble
    when running multi-threaded.
  * There may be two different issues here.
  * Richard speculated that there is some sort of race condition when
    running multi-threaded.
  * Simon tried to reproduce the error under Valgrind, without success
    (i.e., it worked).

      Review of Minutes from the Last HDGeant4 Meeting

We went over the minutes from the meeting on October 18 
Igal will enforce an upper limit on the single-block FCAL energy in 
mcsmear to avoid values in excess of 8 GeV.

      FAQ of the Fortnight: What are "directory tags?"

Mark led us through the FAQ 

      Package Structure

Mark led us through a series of diagrams 
illustrating the dependency structure of our software packages along 
with a proposal for a new structure. Find his explanation starting at 
55:54 in the recording.

He proposes a structure such that the simulation code (halld_sim and 
hdgeant4) does not depend on the "reconstruction" code (halld_recon). 
This should be possible since simulation is performed before 
reconstruction, everywhere and always. The current structure has 
halld_sim and hdgeant4 dependent on halld_recon, not because of the 
details of reconstruction, but due to other support functions that 
happen to live in the halld_recon repository, in particular I/O routines 
and magnetic-field handling.

To obtain independence of simulation from reconstruction, he proposed a 
new package, hd_interface, that captures all code from halld_recon upon 
which simulation depends. The weakness in the scheme is that a naive 
capture of source files from halld_recon into hd_interface, while 
allowing a build of halld_sim and hdgeant4 independent of halld_recon, 
likely gives an interface library that impacts reconstruction. The 
impact is clearly less than that which comes with dependence on the 
whole of halld_recon, still it diminishes the utility of the new 
interface library. The extent of the diminution needs review going forward.

      Action Item Review

 1. Create a Wiki page of Doxygen links. (Mark)
 2. Add Alex to the gluex_admin team on GitHub. (Mark)
 3. Add non-privileged pull-request-re-test procedure to the FAQ.
 4. Figure out why Beni's Doxygen-related pull request does not return a
    result from the automatic test.

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