[8.0] Fix memory reporting

[fstagni]

After #7509

BEGINRELEASENOTES

*WMS
FIX: Fix memory reporting

ENDRELEASENOTES

[arrabito]

I think that computing the MemoryUsed as the difference between the last measured value of RSS and the initial value is fine in most of the cases. However it seems to me that it does not take into account eventual peaks of memory usage during the program execution. So I'm wondering if it wouldn't make sense to add another parameter "PeakMemoryUsed" or "MaxMemoryUsed".
Anyway this could go in a separate PR.

[fstagni]

I think you can propose this in a different PR.

[arrabito]

ok fine for me. I will not do it immediately but I keep it in mind.

[arrabito]

To be consistent I suggest that we use MB also for the Memory parameter.

[arrabito]

I've just added an "approve" review but I see thate Merging is still blocked.
Is it normal or some other actions is needed from my side?

[DIRACGridBot]

Sweep summary

Sweep ran in https://github.com/DIRACGrid/DIRAC/actions/runs/8329879707

Failed:

• integration
  cherry-pick 108861c into integration failed
  check merge conflicts on a local copy of this repository

  git fetch upstream
  git checkout upstream/integration -b cherry-pick-2-108861c3f-integration
  git cherry-pick -x -m 1 108861c3f
  # Fix the conflicts
  git cherry-pick --continue
  git commit --amend -m 'sweep: #7518 Fix memory reporting' --author='Federico Stagni <[email protected]>'
  git push -u origin cherry-pick-2-108861c3f-integration
  
  # If you have the GitHub CLI installed the PR can be made with
  gh pr create \
       --label 'sweep:from rel-v8r0' \
       --base integration \
       --repo DIRACGrid/DIRAC \
       --title '[sweep:integration] Fix memory reporting' \
       --body 'Sweep #7518 `Fix memory reporting` to `integration`.
  
  Adding original author @fstagni as watcher.
  
  BEGINRELEASENOTES
  
  *WMS
  FIX: Fix memory reporting
  
  ENDRELEASENOTES
  Closes #7520'