Hmbown/CodeWhale · error · PersistenceBacklogError

rss_during_delta_bytes is inconsistent

Error message

rss_during_delta_bytes is inconsistent

What it means

On the RSS-supported (macOS) lane, rss_during_delta_bytes must equal max(0, rss_during_bytes - rss_before_bytes): the delta is a derived field clamped at zero, and it must be arithmetically consistent with the raw samples. A mismatch means the receipt's deltas were computed or edited independently of the samples, breaking the measurement's internal consistency.

Solutions

1. Re-run the measurement so deltas are recomputed from the same samples as the raw byte counts.
2. Fix the generator to derive deltas exactly as max(0, during - before) at receipt-write time.
3. Never edit deltas independently; if a ceiling fails, tighten or justify the budget instead of altering the receipt.

Example fix

// before
{"rss_before_bytes": 100, "rss_during_bytes": 90, "rss_during_delta_bytes": -10}
// after
# delta = max(0, during - before)
{"rss_before_bytes": 100, "rss_during_bytes": 90, "rss_during_delta_bytes": 0}

def rss_deltas_consistent(receipt):
    before = receipt.get("rss_before_bytes", 0)
    return (
        receipt.get("rss_during_delta_bytes") == max(0, receipt.get("rss_during_bytes", 0) - before)
        and receipt.get("rss_after_delta_bytes") == max(0, receipt.get("rss_after_bytes", 0) - before)
    )

def is_non_negative_int(v):
    return isinstance(v, int) and not isinstance(v, bool) and v >= 0

try:
    validate_receipt(receipt)
except PersistenceBacklogError as e:
    print(f"rss delta mismatch: {e}", file=sys.stderr)
    sys.exit(2)

When it happens

Trigger: Raised by validate_receipt (macOS lane only, after rss_supported passes) when receipt['rss_during_delta_bytes'] != max(0, receipt['rss_during_bytes'] - receipt['rss_before_bytes']), from validate_baseline_receipt or compare.

Common situations: Recomputing raw RSS samples after a re-run while leaving stale deltas; a generator that clamps deltas differently (e.g. without max(0, ...)); hand-editing a delta to fit under a ceiling in the budget file.

Understand the failure class

Background: Checksum mismatch errors: "checksum verification failed", "digest mismatch", "expected vs actual checksum" — what they mean and how to fix them — this error's family across 41 libraries.

Related errors

• accepted_requests must equal requests_attempted; sender…
• applied_version is not the final sent version
• estimated_retained_payload_bytes is smaller than the frozen…
• final_version_applied must be true
• limitations must be a non-empty string array

AI-assisted analysis of Hmbown/CodeWhale@433685b202 (2026-09-15). Data as JSON: /api/errors/9fb568fa2d2df175. Report an issue: GitHub.

Appendix: source

Thrown at scripts/check-persistence-backlog-budget.py:233

        isinstance(item, str) and item for item in limitations
    ):
        raise PersistenceBacklogError("limitations must be a non-empty string array")

    if not isinstance(receipt["rss_supported"], bool):
        raise PersistenceBacklogError("rss_supported must be boolean")
    if receipt["rss_supported"] != (platform == "macos"):
        raise PersistenceBacklogError(
            "rss_supported must be true exactly on the macOS measurement lane"
        )
    rss_fields = RSS_SAMPLE_FIELDS + RSS_DELTA_FIELDS
    if receipt["rss_supported"]:
        for field in rss_fields:
            non_negative_integer(receipt[field], field)
        before = receipt["rss_before_bytes"]
        if receipt["rss_during_delta_bytes"] != max(
            0, receipt["rss_during_bytes"] - before
        ):
            raise PersistenceBacklogError("rss_during_delta_bytes is inconsistent")
        if receipt["rss_after_delta_bytes"] != max(
            0, receipt["rss_after_bytes"] - before
        ):
            raise PersistenceBacklogError("rss_after_delta_bytes is inconsistent")
    elif any(receipt[field] is not None for field in rss_fields):
        raise PersistenceBacklogError("unsupported RSS fields must be null")


def validate_budget(budget: dict[str, Any]) -> None:
    if budget.get("document_kind") != BUDGET_KIND:
        raise PersistenceBacklogError(f"budget document_kind must be {BUDGET_KIND}")
    if budget.get("schema_version") != SCHEMA_VERSION:
        raise PersistenceBacklogError("budget schema_version changed")
    fixture = budget.get("fixture")
    if not isinstance(fixture, dict) or set(fixture) != set(FIXTURE):
        raise PersistenceBacklogError("budget fixture no longer matches the frozen workload")
    for field, expected in FIXTURE.items():
        if type(fixture[field]) is not type(expected) or fixture[field] != expected:

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