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parallel solve: serial by default until the javascript arm64 race is fenced - #1870
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The cross-language fill pass found a residual crash the seqlock-fix-3 overlay does not cover: the javascript engine under -j8 on darwin-arm64 with concurrent load exits on a segmentation violation ~3/10, each time inside a DIFFERENT rule — shared-structure corruption, not a rule defect. javascript is the only program that creates symbols at solve time (substr/cat in its module rules), so concurrent symbol-table insertion is the suspect; x86 runs (TSO) and quiet or debugger-slowed runs are clean, which fits a weak-memory publication race. Until that structure is fenced like the BTree was, the default build is serial everywhere and AXIOM_SOLVE_PARALLEL=1 opts a machine in. Measured on identical facts with the current rules: opt-in -j8 on quiet darwin-arm64 is worth 1.5-3x (python 122s->40s, csharp 22s->15s) and still ~2x under full load; on 8-vCPU cloud instances it is a slight loss, so nothing is given up by defaulting serial. Co-authored-by: axiomcode-bot[bot] <334110751+axiomcode-bot[bot]@users.noreply.github.com>
swapnilpaliwal-sd
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Whua689 and
suyashpaliwal26
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October 8, 2026 18:49
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Working on a fix instead of this rollback. |
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#1861 merged with the parallel flavor as the default build wherever the toolchain takes OpenMP. The cross-language fill pass then found a crash that gate's evidence did not cover: the javascript engine under
-j8on darwin-arm64 with concurrent memory-pressure load segfaults ~3/10, each time in a different rule — a shared structure the seqlock-fix-3 overlay does not fence (#1869 has the full diagnosis and repro; concurrent solve-time symbol creation is the suspect, unique to the javascript program).This flips the default back to serial everywhere;
AXIOM_SOLVE_PARALLEL=1remains the one-variable opt-in and still buys 1.5–3x on quiet multicore hardware with the current rules (python 122s→40s, csharp 22s→15s on an arm64 Mac; ~2x under full load). On 8-vCPU cloud instances parallel measured as a slight loss on the current rules, so the serial default costs nothing there.Closes nothing; the fence for #1869 re-enables the default in its own gated change.