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Bugfix: a parallel loop's iterations share the job's cores - #43

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Oct 22, 2026
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  • A parallel loop gave each iteration one core by default, so four replicas in a
    64-core job ran on four cores (job 5368). "Cores per iteration" now defaults to
    automatic: the job's cores shared among the iterations that run at once, e.g.
    16 each for four replicas in a 64-core job. A number is used as given;
    flowcharts saved with 1 keep it, so set them to automatic.
  • The settings that say only how the iterations run -- iterations at once, cores,
    memory and time per iteration, and where the calculations run -- can now be
    changed before resuming the job (needs seamm 2026.10.22).

Requires seamm>=2026.10.22 (molssi-seamm/seamm PR): CI here fails until that is
released, since the current seamm rejects the new 'resource' marking.

🤖 Generated with Claude Code

'automatic' (the new default) shares the job's cores among the iterations that
run at once (iteration_cores); the default of 1 left 60 of 64 cores idle in job
5368. The resource settings are marked so seamm 2026.10.22's fingerprint
ignores them and a resume survives changing them. Requires seamm>=2026.10.22.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@paulsaxe paulsaxe added the bug Something isn't working label Oct 22, 2026
@paulsaxe
paulsaxe requested a review from seamm October 22, 2026 15:09

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LGTM

@seamm
seamm merged commit 43a8b89 into main Oct 22, 2026
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