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parallel solve: serial by default until the javascript arm64 race is fenced #1870

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parallel solve: serial by default until the javascript arm64 race is fenced #1870

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22 changes: 10 additions & 12 deletions graph/pipeline/run-souffle.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -555,18 +555,16 @@ case "${AXIOM_SOLVE_PARALLEL:-}" in
1) if _OMP="$(probe_openmp)"; then
OMP_FLAG=($_OMP); PAR_SUFFIX="-par"
fi ;;
"") # Parallel by default on every platform with evidence behind it. The two arm64
# weak-ordering holes (write-entry RMW; unfenced node publication) are closed by
# the seqlock-fix-3 overlay, validated under load: darwin-arm64 10/10, linux-arm64
# 10/10 (GCP), linux-x64 5/5 (GCP) — all relation-identical to serial. x64 is TSO,
# where neither hole is observable. Windows local compiles probe like the rest
# (MSYS g++); packaged win32 engines carry /openmp from build-engines.yml, gated
# by its own release validation. AXIOM_SOLVE_PARALLEL=0 is the one-variable
# rollback to serial anywhere, no rebuild.
if _OMP="$(probe_openmp)"; then
# shellcheck disable=SC2206 — the probe emits simple flags, split wanted
OMP_FLAG=($_OMP); PAR_SUFFIX="-par"
fi ;;
"") # Serial by default everywhere. The seqlock-fix-3 overlay closed the two diagnosed
# arm64 ordering holes, but the javascript program — the only one that creates
# symbols at solve time (substr/cat in its module rules) — still segfaults ~3/10
# under -j8 on darwin-arm64 with concurrent load, in a different rule each time:
# a shared structure the fix does not cover (symbol-table insertion suspected).
# Until that is root-caused and fenced, parallel is opt-in: AXIOM_SOLVE_PARALLEL=1
# builds the -par flavor on any machine whose toolchain takes OpenMP. On quiet
# multicore hardware it is worth 1.5-3x on top of the rule work (python 122s->40s
# darwin-arm64); on 8-vCPU cloud instances it measured as a slight loss.
;;
esac
EXE=""; case "$(uname -s)" in MINGW*|MSYS*|CYGWIN*) EXE=".exe";; esac
BIN="$CACHE_DIR/souffle-engine-$LANG_ARG-$ENGINE_ID$PAR_SUFFIX$EXE"
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