The three-shard backend gate landed with a 16 GiB admission requirement
that exceeded the 8-vCPU PVE worker's own idle availability (measured
16.1-16.7 GiB, and 14.1-14.9 GiB beside the sibling release compilers),
so the next release would have hard-failed at admission before running a
single test. Direct probes on the worker measured the complete gate at a
~6-7.5 GiB footprint (8.9 GiB MemAvailable floor from a 16.4 GiB start,
zero swap), so admission now requires 10 GiB for three shards and 8 GiB
for two, and degrades the shard count instead of failing the release
when the bounded wait expires without headroom.
Shard CPU is now weighted by planned test volume from the plan manifest.
Top-level tests execute serially per test-binary process, so width mainly
buys runtime, GC, and race-detector headroom for the 3595-test prefix
shard; the ~15-test wait-bound tails cannot use it. Probes measured the
prefix shard at 569s with 2 procs versus 484s with 4, with total
allocation still equal to the worker's vCPU count.
Validated by three direct runs of the canonical script on the worker:
the full gate passed in 8m10s wall (auto-admitted three shards, procs
4/2/2, shard walls 484s/331s/224s) against the 12m09s two-shard release
job measured in run 32514803052. One rig run also proved the gate fails
closed: a stale contract pin failed the non-API graph and the harness
terminated every descendant shard process.
