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core: AOT context image — init-cached recovers the bootstrap cost across processes

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init in compile mode is ~2.4 s (tier loading, analyzer self-compile, macro
recompilation), paid by every process that builds a ctx from source — each
jpm-test file, embedders, workers. init-cached marshals the built ctx to a
disk image (same root-env dicts as snapshot/fork) and later processes
unmarshal it in ~5 ms, any process: nothing from the baking process is
needed at load.

The cache key fingerprints the embedded .clj stdlib (which covers jolt-core:
analyzer, IR, core tiers), the .janet seed sources next to the module, the
janet version, the init opts, and the env knobs that shape a ctx (JOLT_PATH/
MUTABLE/AOT_CORE/FEATURES) — any change rebuilds. Corrupt or non-ctx images
fall back to a rebuild (unmarshal of garbage can 'succeed' with a scalar, so
the shape is checked, not just the throw). Writes are atomic (tmp + rename)
so racing cold starts never publish a torn image. JOLT_NO_IMAGE_CACHE=1
opts out; JOLT_IMAGE_CACHE_DIR overrides the location (default TMPDIR).

Test consumers switch to init-cached (harness, suite-worker, conformance,
the behavioral unit/integration tests); tests that validate the bootstrap
itself (bootstrap-fixpoint, staged-bootstrap, aot round-trip, direct-linking)
and the deps tests (tmp-dir :paths would fragment the key) keep real init.
Full jpm test: 2:46 -> 1:58 (~29%). New ctx-image-test covers cold/warm,
cross-process load (subprocess runs defn/redef/macros/protocols/multimethods
off the baked image), per-opts keying, and corrupt-image fallback.
This commit is contained in:
Yogthos 2026-06-10 13:57:37 -04:00
parent bf885078f9
commit 0e3584884f
24 changed files with 222 additions and 64 deletions
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4
test/integration/dispatch-cache-test.janet
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@ -15,7 +15,7 @@
(printf "FAIL [%s] got %q want %q" label got want)))
(each mode [{:compile? true} {} {:aot-core? false}]
(def ctx (init mode))
(def ctx (init-cached mode))
(eval-string ctx "(defprotocol P (m [x]))")
(eval-string ctx "(extend-protocol P Number (m [x] (* x 2)))")
(check (string mode " host dispatch") (eval-string ctx "(m 5)") 10)
@ -31,7 +31,7 @@
# Multimethod hierarchy-fallback cache (jolt-g8w): the isa? walk result for a
# dispatch value is cached; defmethod/remove-method must invalidate it.
(each mode [{:compile? true} {} {:aot-core? false}]
(def ctx (init mode))
(def ctx (init-cached mode))
(eval-string ctx "(derive ::circle ::shape)")
(eval-string ctx "(derive ::square ::shape)")
(eval-string ctx "(defmulti area identity)")