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perf(ci): stabilize file mtimes for Go test cache #19395

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Merged
davdhacs merged 6 commits into from
Mar 31, 2026
Merged

perf(ci): stabilize file mtimes for Go test cache #19395

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f0d4302
perf(ci): stabilize file mtimes for Go test cache
davdhacs Mar 24, 2026
0e3e889
perf(ci): also stabilize directory mtimes for test cache
davdhacs Mar 26, 2026
b313cbf
fix: use TZ=UTC for mtime stabilization
davdhacs Mar 28, 2026
83baecf
Merge remote-tracking branch 'origin/master' into davdhacs/test-cache…
davdhacs Mar 31, 2026
a04654b
fix: remove TZ=UTC from mtime stabilization (all runners are UTC)
davdhacs Mar 31, 2026
2087aec
Merge remote-tracking branch 'origin/master' into davdhacs/test-cache…
davdhacs Mar 31, 2026
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17 changes: 17 additions & 0 deletions .github/actions/cache-go-dependencies/action.yaml
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Expand Up @@ -71,3 +71,20 @@ runs:
find "$gocache" -mindepth 1 -type d -empty -delete 2>/dev/null || true;
after=$(du -sm "$gocache" 2>/dev/null | cut -f1);
echo "GOCACHE trimmed: ${before:-0}MB -> ${after:-0}MB (removed $((${before:-0} - ${after:-0}))MB)"

- name: Stabilize file mtimes for Go test cache
run: |
# Go's test cache validates inputs by (path, size, mtime) — NOT content.
# git checkout sets all mtimes to "now", which differs between CI runs,
# causing every test to miss the cache. Setting a fixed mtime makes the
# test cache hit across runs when file content hasn't changed.
#
# Risk: if a non-.go testdata file changes content but not size between
# commits, the test cache could return a stale result. This is extremely
# rare and Go's own test cache has the same inherent limitation.
git ls-files | xargs touch -t 200101010000
# Also stabilize directory mtimes — tests using os.ReadDir or
# filepath.Walk check directory mtimes too. git ls-files only
# lists files, not directories.
git ls-files | sed 's|/[^/]*$||' | sort -u | xargs touch -t 200101010000
shell: bash
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