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Martin Vogel
da3258f3c7
Memory in this project is now allocated through ONE core. This lands the
core, the gate that keeps new code on it, and the instrumentation that lets
an index run say which class of memory grew in which pass -- the three things
the 2026-09-13 audit found missing.
WHAT THE AUDIT FOUND
There was no centralized allocation layer. foundation/mem.h was policy and
measurement only (budget, RSS, over_budget, memory map, phase marks) with no
alloc/free wrapper, so the budget could be observed after the fact and never
enforced. Raw allocator calls in the tree: 4086 across 92 files. The
extraction engine had already adopted arenas (1301 call sites); the graph
buffer -- which holds the 35 GB peak of a kernel index -- used none,
allocating every 64 B node, 48 B edge and every name/qualified_name/
properties_json individually.
Two further facts made a self-accounting core the only workable design:
1. cbm_mem_map_collect() walks THIS thread's mimalloc heap only. Walking
the process-wide heap is a data race TSan caught on macOS, so it is
deliberately not done, and an 18-worker index attributes almost
nothing -- the rest lands in residual.
2. The mimalloc global override is ON for Linux/MinGW and permanently OFF
for macOS (two-level namespace: this binary's free becomes mi_free while
system libraries keep allocating from the system zone, and a pointer
crossing that boundary aborts). On macOS ordinary malloc is served by
the system allocator; the startup audit reports owned_classes=0/6. Any
accounting that assumes mimalloc owns the pointer is blind on an entire
platform.
THE CORE (src/foundation/mem_core.{h,c})
cbm_alloc / cbm_calloc / cbm_realloc / cbm_mem_strdup / cbm_free, each tagged
with an allocation class (gbuf_node, gbuf_edge, gbuf_string, gbuf_index,
extract, semantic, dump, store, other). Per-class live bytes, live blocks and
peak, kept in atomics -- thread-safe by construction, identical on every
platform, independent of which allocator serves malloc. libc semantics are
preserved exactly (alloc(0) is freeable, free(NULL) is a no-op, realloc(NULL)
allocates, a failed realloc leaves the block intact) so adoption is a
mechanical rename and never a behaviour change.
No per-allocation header: a {class,size} prefix costs 16 bytes on ~100M blocks
at kernel scale, 1.6 GB of overhead to measure a memory problem. Sizes come
from the platform usable-size query (malloc_size / malloc_usable_size /
_msize), which is correct under either allocator and free. Where no query
exists (BSD) the request size is charged, which understates -- the safe
direction for a diagnostic. A mismatched class on free clamps at zero rather
than wrapping, so a small drift can never masquerade as a colossal leak.
Arena-backed allocators report in bulk through cbm_mem_class_add_external /
remove_external so their memory appears in the same table; the extraction
engine must not be rewritten to per-object allocation, that would undo the
batching that keeps its allocation count low.
THE LINTER (scripts/lint-memory-core.py, wired into make lint-ci)
Raw malloc/calloc/realloc/free/strdup/strndup outside the core is a defect.
4086 sites cannot migrate at once, so the gate is a ratchet: a checked-in
baseline (scripts/memory-core-baseline.txt) records each file's count and
the build goes red when any file grows, or a new file appears with any.
Files only ever go down; the baseline line is lowered in the change that
migrates the file, and --strict fails a stale baseline. Comments and string
literals are stripped first, so prose that mentions malloc( cannot trip it --
the security audit already bit on exactly that with fork(. Proven both ways:
one appended malloc turns it red naming the file (83 -> 85), restoring turns
it green. Scans src/ and internal/cbm/: cli, mcp, daemon, store, pipeline.
PHASE ATTRIBUTION (src/pipeline/pipeline.c)
cbm_mem_phase_mark and the new cbm_mem_class_log now fire at pipeline.begin
and at every pass.timing site: parallel_extract, the six sequential passes,
the eight predump passes, tests and dump_and_persist, with peaks reset per
index. Both instruments existed in foundation/ and were wired only into MCP
request handling, never into the index pipeline -- which is where the memory
is. Locating the kernel peak this week required an external RSS sampler
because nothing in-process could say which phase it was in.
PRESSURE PRIMITIVES (system_info.c, mem.{c,h}, platform.h)
cbm_system_available_ram() -- macOS host_statistics64 (free + inactive +
purgeable), Linux MemAvailable, Windows GlobalMemoryStatusEx; 0 when unknown,
never cached -- and cbm_mem_system_under_pressure(), true below 12.5% of RAM
available and false when unknown so nothing ever aborts on a guess. Landed
UNWIRED: an earlier draft used them to let the over-budget latch press on
whenever the system was not under pressure, and that permitted the very
overshoot this work exists to end (Decision A's tests at
test_pipeline.c:13481 and :13583 went red under it, correctly). They are the
backstop for the next step, admission control, which keeps a run under budget
before an allocation rather than measuring it after.
mem suite 10 new tests green; pipeline + mem 339 passed 0 failed; lint-ci
clean including the new gate.
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>