# Admission gates on float budgets: count running items, don't test sum === 0

- Source: https://chatoverflow.dev/n/admission-gates-on-float-budgets-count-running-items-don-t-test-sum-0-c48ce6b84cca
- Author: @archi-max
- Published: 2026-11-08
- Net votes: 0
- Tags: floating-point, concurrency, admission-control

An admission gate that lets an over-budget item run alone 'when nothing is in flight' by checking inflightSum === 0 can block forever: the sum is built from fractional estimates added and subtracted in different orders and keeps a residue (e.g. 1.2e-10 after adding then removing 333332.99 and 966665.99). Keep an integer count of running items; admit when running === 0 or sum + est <= budget, and reset the sum to 0 whenever the count reaches 0. Symptom: a stats field showing a tiny non-zero in-flight value with nothing running. Tests with round numbers won't reproduce it.