Development record
2026-09-25 — The load check's stray rule is "busy for its share" (ruling H1, the product thinker via the interview session, 07:57Z, on iss-2609231947544298). A long-running process outside abcd's lanes is a stray when it uses nearly all the CPU it could get on the machine as loaded: its lifetime CPU share is measured against its fair share, the online cores divided by the runnable demand, not against a fixed 0.9 of one core, so forty busy loops each at a fortieth of the machine all count. The share test applies to the caller's own processes and to other accounts' alike, and other accounts' strays stay counted only. It is not a second sample and not a summed-cores trigger. The build reads the runnable demand as the snapshot's one-minute load average and caps the fair share at one core, so on a machine loaded no higher than its cores the rule is the near-full core it was (`machineload.FairShare`, spc-2609232027132755). This closes the band between 1.125 and 4 times the cores in which the check said nothing (pinned by `TestStrayRuleSilentBand`, succeeded by `TestStrayRuleCoversTheOversubscribedBand`), and lets the load check's remainder spec close and itd-2609231434459890 ship. The check still warns and never refuses (the 2026-09-23 entry above on that intent).
2026-09-25 — The load check's stray rule is "busy for its share" (ruling H1, the product thinker via the interview session, 07:57Z, on iss-2609231947544298). A long-running process outside abcd's lanes is a stray when it uses nearly all the CPU it could get on the machine as loaded: its lifetime CPU share is measured against its fair share, the online cores divided by the runnable demand, not against a fixed 0.9 of one core, so forty busy loops each at a fortieth of the machine all count. The share test applies to the caller's own processes and to other accounts' alike, and other accounts' strays stay counted only. It is not a second sample and not a summed-cores trigger. The build reads the runnable demand as the snapshot's one-minute load average and caps the fair share at one core, so on a machine loaded no higher than its cores the rule is the near-full core it was (machineload.FairShare, spc-2609232027132755). This closes the band between 1.125 and 4 times the cores in which the check said nothing (pinned by TestStrayRuleSilentBand, succeeded by TestStrayRuleCoversTheOversubscribedBand), and lets the load check's remainder spec close and itd-2609231434459890 ship. The check still warns and never refuses (the 2026-09-23 entry above on that intent).
Frontmatter
| id | dcn-2609250000000012 |
|---|---|
| type | decision |
| date | 2026-09-25 |
.abcd/work/decisions/dcn-2609250000000012-the-load-check-s-stray-rule-is-busy-for.md
open on GitHub ↗ · commit history ↗
mentions3
- iss-2609231947544298The load check's stray rule is silent across a load band that itd-2609231434459890's Mechanism, Decision 1 and Grounds claim it covers. A process is a stray only when it is older than the stray limit and its lifetime share of a core is at least 0.9 (NearFullShare, internal/core/machineload/classify.go); the extreme trigger fires only when the one-minute load is strictly above four times the online cores. Busy loops that have run for days each hold their fair share, cores divided by their count, so on 16 cores at the default limits: 17 loops (0.94 of a core each) warn through the stray trigger; 18, 20, 40 or 64 loops, a load between 1.125 and 4 times the cores, each hold under 0.9 of a core and raise no trigger, so the check is silent (no warning, no run-log event); from 65 loops the warning is the extreme trigger's alone, as at the 2026-09-22/23 incident's load of about 440, where the stray count read 0. The share filter applies before the uid split, so the band silences the caller's own loops as well as another account's. The fixture that shows it is TestStrayRuleSilentBand in internal/core/machineload/classify_test.go (TestMechanismFlagsIncidentTwo pins the 440 case). Major: the check's main purpose, flagging a forgotten busy loop, fails silently in the band, and the intent's Grounds say it is shown wrong by exactly that. The remainder spec spc-2609232027132755 holds the intent planned on this band. Fixing it needs a ruling on the stray definition (a share relative to what the machine could give the process, or a second sample), which the lane cannot take.
- itd-2609231434459890abcd's own tests warn before running on an overloaded machine
- spc-2609232027132755stray-rule-silent-band