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ci: re-enable CGAL tests with LOW_MEMORY_BUILD for Raspberry Pi runner

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Finding-I from doc/reviewer/external-audit-2026-05-30.md.

Root cause: CGAL+Eigen at -O3 drives cc1plus peak RAM to ~700 MB per
Unity compilation unit (batch size 4) on ARM64.  With the 1600 MB
container limit the 2nd or 3rd TU reliably triggered OOM-kill, so
test-cgal was gated off via `if: false` since 2026-05-26.

Fix: new CMake option CONFORMALLAB_LOW_MEMORY_BUILD=ON applies four
orthogonal memory-saving measures to conformallab_cgal_tests:

  1. -O0 (no debug info): optimizer passes entirely skipped → cc1plus
     peak drops from ~700 MB to ~150-200 MB per TU on ARM64.
     Omitting -g avoids the additional object-file / linker RAM cost.

  2. CONFORMALLAB_USE_PCH=OFF: saves the one-time ~200 MB PCH
     compilation cost; each TU re-parses CGAL headers (fast at -O0).

  3. UNITY_BUILD_BATCH_SIZE=1: one source file per cc1plus invocation,
     removing the "4-file template-explosion" per-unit multiplier.

  4. -Wl,--no-keep-memory (GNU ld): linker releases symbol tables after
     each input file → ~15-25 % less linker RSS.

Verified locally with cmake -DCONFORMALLAB_LOW_MEMORY_BUILD=ON:
  277/277 CGAL tests pass, 31 s runtime (vs 2 s at -O3 — expected;
  tests run 15× slower without optimizer but all correct).

CI workflow changes (cpp-tests.yml):
  - test-cgal re-enabled: `if: github.event_name == 'pull_request'`
  - Configure step adds -DCONFORMALLAB_LOW_MEMORY_BUILD=ON
  - Container memory: 1600m → 2000m (--memory-swap=3000m for 1 GB swap
    headroom), using ~half of the Pi's 3-4 GB while leaving OS margin.

CLAUDE.md updated: new flag added to compile-time options table; CI
status row corrected from DISABLED to active.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Tarik Moussa
2026-05-31 00:57:28 +02:00
parent 59a26123c8
commit 449c5899c0
4 changed files with 100 additions and 31 deletions
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CLAUDE.md
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@@ -56,6 +56,7 @@ The CGAL test build defaults to **PCH + Unity Build ON** (CGAL test wall-time 78
| `-DCMAKE_UNITY_BUILD=OFF` | ON | Disable Unity (jumbo) build. |
| `-DCONFORMALLAB_DEV_BUILD=ON` | OFF | Dev iteration: PCH on, Unity forced off (cheaper incremental rebuilds). |
| `-DCONFORMALLAB_FAST_TEST_BUILD=ON` | OFF | `-O0 -g` for tests (faster compile, slower run). |
| `-DCONFORMALLAB_LOW_MEMORY_BUILD=ON` | OFF | **RAM-constrained CI** (Raspberry Pi): `-O0` (no -g), PCH off, unity batch 1, `--no-keep-memory` linker. Drops cc1plus peak from ~700 MB to ~150-200 MB per TU so the CGAL build fits in a 2 GB container. Tests run ~15× slower but all pass. Use with `-j1`. |
| `-DCONFORMALLAB_USE_CCACHE=ON` | OFF | Route compiles through ccache. |
| `-DCONFORMALLAB_HEADERS_CHECK=ON` | OFF | Standalone header self-containment check target. |
@@ -264,14 +265,14 @@ Three jobs in `.gitea/workflows/cpp-tests.yml`:
| Job | CMake flags | Deps | Triggers on | Status |
|---|---|---|---|---|
| `test-fast` | *(none)* | Eigen + GTest only | all branches | **active** |
| `test-cgal` | `-DWITH_CGAL_TESTS=ON` | + Boost | pull requests only | **DISABLED 2026-05-26** (`if: false`) |
| `test-cgal` | `-DWITH_CGAL_TESTS=ON -DCONFORMALLAB_LOW_MEMORY_BUILD=ON` | + Boost | pull requests only | **active** (re-enabled 2026-05-31) |
| `quality-gates` | *(none)* | + codespell, shellcheck | all branches (`needs: test-fast`) | **active** |
Runner: `eulernest` — self-hosted Raspberry Pi, ARM64, Ubuntu 22.04. Docker image: `git.eulernest.eu/conformallab/ci-cpp:latest`. `test-cgal` and `quality-gates` both need `test-fast` to pass first (`needs: test-fast`).
`quality-gates` runs four required structural gates: `license-headers.sh`, `cgal-conventions.py`, `codespell.sh`, `shellcheck.sh --strict`. Seven more gates (clang-format, cmake-format, cppcheck, sanitizers, clang-tidy, multi-compiler, reproducible-build) are local-only — see `scripts/quality/README.md`.
**`test-cgal` is gated off** (`if: false`, see the DISABLED-2026-05-26 comment block in the workflow): the `-j1` CGAL build is too memory-heavy for the 1.6 GB runner and OOMs intermittently without exposing real regressions. Consequence: the two structural sub-gates that lived inside it — `scripts/check-test-counts.sh` and `scripts/try_it.sh` — are currently **un-gated**; run them locally before tagging a release. Re-enable by restoring `if: github.event_name == 'pull_request'`.
**`test-cgal` re-enabled 2026-05-31** with `CONFORMALLAB_LOW_MEMORY_BUILD=ON`: uses `-O0` (no debug info), PCH off, unity batch size 1 and `--no-keep-memory` linker flag. This drops cc1plus peak RAM from ~700 MB to ~150-200 MB per TU, fitting within a 2000 MB container on the 3-4 GB Raspberry Pi runner. Container memory raised from 1600 → 2000 MB (with 1000 MB swap headroom). Tests run ~15× slower at -O0 but all 277 pass. The two structural sub-gates (`scripts/check-test-counts.sh`, `scripts/try_it.sh`) remain inside the CGAL job and run after the test step.
Two other workflows are also restricted to `workflow_dispatch:` only (auto-trigger disabled 2026-05-26 while the codeberg pages-branch push is being stabilised):
- `.gitea/workflows/doxygen-pages.yml` — publishes Doxygen HTML + reviewer hub to the codeberg `pages` branch.