build_uw3_and_test.yaml referenced "the CI-runtime issue" as the home for the
durable fix to wall-clock. That issue was never actually filed. This is it, with
the measurements.
Where it stands
The 120-minute cap was set on a 2026-08-15 measurement putting the serial phase
alone at ~55 minutes, before xdist distributed the batches. Measured 2026-09-12,
the five most recent successful runs spent this long in "Run tests":
34m19s development
35m23s development
42m32s feature/particle-demos
44m20s docs/tier-c-characterisation-tests
47m34s docs/timestepping-pattern
That headroom is why the previously-deferred bands could simply be switched on
rather than traded against something else.
The fix, for when it is needed
Split the batches across parallel GitHub jobs so wall-clock stops tracking total
test time. The serial phase already falls into natural groups that map onto a
job matrix without restructuring scripts/test.sh much:
test_00*-test_03*test_05*-test_08*test_10*-test_14*- the
--p N mpirun phase, which runs its own batches
Not yet, though
Doing it now would be machinery ahead of need. The single job fits inside its
budget with room, and every job added pays the ~2.5 min build again unless the
build artefact is shared between them — which is the part that needs designing,
not the matrix.
Worth revisiting when "Run tests" passes roughly 70 minutes, or when the build
step can be cached across jobs.
Underworld development team with AI support from Claude Code
build_uw3_and_test.yamlreferenced "the CI-runtime issue" as the home for thedurable fix to wall-clock. That issue was never actually filed. This is it, with
the measurements.
Where it stands
The 120-minute cap was set on a 2026-08-15 measurement putting the serial phase
alone at ~55 minutes, before xdist distributed the batches. Measured 2026-09-12,
the five most recent successful runs spent this long in "Run tests":
That headroom is why the previously-deferred bands could simply be switched on
rather than traded against something else.
The fix, for when it is needed
Split the batches across parallel GitHub jobs so wall-clock stops tracking total
test time. The serial phase already falls into natural groups that map onto a
job matrix without restructuring
scripts/test.shmuch:test_00*-test_03*test_05*-test_08*test_10*-test_14*--p Nmpirun phase, which runs its own batchesNot yet, though
Doing it now would be machinery ahead of need. The single job fits inside its
budget with room, and every job added pays the ~2.5 min build again unless the
build artefact is shared between them — which is the part that needs designing,
not the matrix.
Worth revisiting when "Run tests" passes roughly 70 minutes, or when the build
step can be cached across jobs.
Underworld development team with AI support from Claude Code