foamReport: wrong mesh statistics when running in parallel

Summary

When using the foamReport function object on a parallel case, some mesh builtin entries only report values from processor0 (number of cells, faces, points)

Steps to reproduce

Run the motorbike tutorial.

What is the current bug behaviour?

checkMesh output:

Mesh stats

points: 427682

faces: 1127871

internal faces: 1038577

cells: 353724

But foamReport output different values for cells, points and faces:

| Number of cells | 58932 |

| Number of faces | 189342 |

| Number of points | 72863 |

The 58932 cells reported by foamReport correspond to the number of cells in processor0 instead of the total number of cells in the mesh.

Mesh bounds and number of patches are correctly reported.

What is the expected correct behavior?

Report the total number of cells/points/faces in the mesh.

Relevant logs and/or images

log.checkMesh

foamReport1.md

Environment information

• OpenFOAM version : v2412
• Patch : 0
• Build : _45e7c4a0-20241224
• Operating system : WSL (Ubuntu 20.04)

assigned to @mark

I agree. Looks like an oversight (ie, bug) - will get back to you.

Attached is are my current changes - should be more consistent. Could you please check if this does the job for you.

foamReport-test.C

Thanks for the quick fix Mark, I just tested it now and it work as expected, I get the proper mesh statistics now.

I also had a quick, unrelated question: is there a way to retrieve the Hosts list?

We currently have the {{OF_HOST}} key, but I would be interested to get the host lists when running on a cluster. This would be the "Hosts" part which is already reported at the beginning of the solver log, eg:

Build  : _45e7c4a0-20241224 OPENFOAM=2412 version=2412
Arch   : "LSB;label=32;scalar=64"
Exec   : simpleFoam -parallel -decomposeParDict system/decomposeParDict.6
Date   : Mar 13 2025
Time   : 09:35:43
Host   : machine1
PID    : 2530
I/O    : uncollated
Case   : /mnt/c/Users/Yann/OpenFOAM-v2412/motorBike
nProcs : 18
Hosts  :
(
    (machine1 6)
    (machine2 6)
    (machine3 6)
)

Currently no trivial way to retrieve the host names like the startup does.

I won't rule out being able to add this in the future, but that should be handled as a new feature request (not a bug). Ideally (assuming you want the feature), make an attempt at it yourself and then we can review what you have and see how well it integrates. This is not entirely laziness on my part, but it is useful if you can explore it yourself and can then determine how much use it really has (which prevents us from adding code that isn't really useful in the long-term).

The basics of what you need is to collect and sort the hostnames. Probably as a combination of what is in argList with a few changes.

For example,

word host = Foam::hostName();

if (UPstream::master())
{
    HashTable<label> hosts;
    hostMachine.reserve(UPstream::nProcs());

    ++hostNames(host)++;

    for (const int proci : UPstream::subProcs())
    {
        IPstream::recv(host, proci);
        ++hostNames(host);
    }

    for (const auto& iter : hosts.csorted())
    {
        Info<< "host: " << iter.key() << " count:" << iter.val() << nl;
    }
}
else
{
    OPstream::send(host, UPstream::masterNo())
}

Of course with some different type of serialization of the host/count hashed value.

If you are targeting changes for the v2506 release, it might be cheaper to use the updated handling of interNode communication since this will give you a direct count with less communication.

Thank you very much for your feedback and pointers Mark!

I agree this would be a feature request, I just wanted to use the opportunity to ask if there was an easy way to do it. I also totally understand not wanting to add unnecessary code.

For now I'm going to explore the current foamReport capabilities. I'll try to add the hosts list and open a feature request for it if I really miss this information in my reports.

To get back to the mesh statistics bug, your modifications totally do the job for me!

mentioned in commit 0a530134

closed

added community label