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app/backend/fluksio/flow/metrics.py
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stroblmeandClaude Opus 5 37a7df9d24
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Let a sweep run more than four at a time, and name the run a failure was in
Concurrent runs sat at 4 whatever FLOW_MAX_CASCADES said: that setting bounds
cascades, and the run drivers read a hardcoded MAX_PARALLEL nobody could reach.
FLOW_MAX_RUNS is the knob they read now, --max-runs/--max-cascades/--max-workers
are the same three as flags on serve, and the engine says which numbers it
started with — which is the only way to tell that a settings file was read.

Events keep the run they happened in. The payload always carried it and the
persist path dropped it, so reading one run's failures meant filtering the
engine-wide list; a batch run's id reaches those events now too, since a run
has no journaled item to name itself by.

Also: a provisioner's 0 means "no deadline" rather than "cancel on the next
reconcile", and a command that reaches no engine says how to start one.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015sbYeYaVgYQqm1sbx7wPdL
2026-08-27 14:17:51 +02:00

418 lines
16 KiB
Python

"""What the engine did, kept long enough to answer for it.
The event bus already carries every execution, error and cascade; until now
nothing wrote any of it down, so "was it slow yesterday?" had no answer. This
subscriber folds those events into per-minute rollups, keeps the failures and
the audit trail whole, and records one row per cascade.
Accumulation is in memory and flushed every few seconds: a node firing at
10 Hz must not be 10 inserts a second, and the arithmetic that turns it into
one row a minute is cheaper than the round trip would be.
"""
from __future__ import annotations
import asyncio
import logging
import time
from datetime import UTC, datetime, timedelta
from typing import Any
from sqlalchemy import delete, func, update
from sqlalchemy.dialects.sqlite import insert
from sqlmodel import Session, col
from fluksio.core.config import settings
from fluksio.core.db import engine
from fluksio.flow.events import EventBus
from fluksio.models import EngineEvent, FlowRun, MetricBucket
logger = logging.getLogger(__name__)
#: How often the accumulated minute is written out.
FLUSH_INTERVAL_S = 15.0
#: A traceback is worth reading; a whole run of a chatty node is not.
DETAIL_CAP = 8000
#: A cascade still open this long after it started is never finishing.
RUN_STALE_S = 600.0
#: ``metric_minute.flow``/``node`` and ``flow_run.flow`` are this wide, and a
#: node id has no length of its own. One row over it aborts the transaction,
#: which would take every other row in the flush with it.
NAME_MAX = 255
#: How much unwritten history is held while the database is unreachable. Enough
#: for a long outage, bounded so the outage cannot become a memory leak.
HOLD_MAX = 10_000
#: Retention is checked this often, not on every flush.
PRUNE_INTERVAL_S = 3600.0
#: Bucket columns that add up over a minute, and the two that take the larger.
SUMMED = (
"executions",
"errors",
"messages",
"duration_sum_ms",
"lag_sum_ms",
"items",
)
MAXIMA = ("duration_max_ms", "lag_max_ms")
#: Engine events kept as rows. Everything else on the bus is traffic.
RECORDED = {
"flow_quarantined",
"task_crashed",
"engine_degraded",
"engine_fatal",
"cascade_dropped",
"queue_unavailable",
}
def _minute(ts: float) -> int:
"""The epoch second the minute containing ``ts`` starts at.
An integer rather than a datetime: this runs once per event on the API's
event loop, and building a tz-aware datetime to key a dict with cost more
than everything the collector does with the event afterwards. The row
still wants one, so `_write` builds it — once per minute per node rather
than once per event.
"""
return int(ts // 60) * 60
def _detail(event: dict[str, Any]) -> str:
text = str(event.get("error") or event.get("reason") or event.get("detail") or "")
if event.get("type") == "cascade_dropped":
text = f"Given up on after {event.get('deliveries')} deliveries. {text}"
return text[:DETAIL_CAP]
class MetricsCollector:
"""Folds engine events into rollups, failures and run records."""
def __init__(self, events: EventBus, flush_s: float = FLUSH_INTERVAL_S) -> None:
self._events = events
self._flush_s = flush_s
self._buckets: dict[tuple[str, str, int], dict[str, float]] = {}
self._runs: dict[str, dict[str, Any]] = {}
self._pending: list[EngineEvent] = []
# The traceback arrives one event before the failure it belongs to,
# held with the time it arrived so an unpaired one does not stay put.
self._tracebacks: dict[tuple[str, str], tuple[float, str]] = {}
self._last_prune = 0.0
# -------------------------------------------------------------------------
# The loop
# -------------------------------------------------------------------------
async def run(self) -> None:
"""Consume the bus until cancelled, flushing on a fixed interval."""
last = time.monotonic()
async with self._events.subscribe() as queue:
while True:
# A busy bus never idles, so the flush is on a deadline rather
# than on the timeout alone.
timeout = max(0.05, self._flush_s - (time.monotonic() - last))
try:
event = await asyncio.wait_for(queue.get(), timeout)
except TimeoutError:
pass
else:
try:
self.handle(event)
except Exception:
logger.exception("Could not record %s", event.get("type"))
if time.monotonic() - last >= self._flush_s:
await self.flush()
last = time.monotonic()
# -------------------------------------------------------------------------
# Accumulating
# -------------------------------------------------------------------------
def _bucket(self, event: dict[str, Any]) -> dict[str, float]:
# ponytail: one collector, one row per node per minute; coarsen the
# bucket if the node count ever reaches thousands.
key = (
str(event.get("flow") or "")[:NAME_MAX],
str(event.get("node") or "")[:NAME_MAX],
_minute(float(event.get("ts") or time.time())),
)
return self._buckets.setdefault(
key,
{
"executions": 0,
"errors": 0,
"messages": 0,
"duration_sum_ms": 0.0,
"duration_max_ms": 0.0,
"lag_sum_ms": 0.0,
"lag_max_ms": 0.0,
"items": 0,
},
)
def handle(self, event: dict[str, Any]) -> None:
"""Fold one event in. Synchronous: this is arithmetic on dicts."""
kind = str(event.get("type") or "")
ts = float(event.get("ts") or time.time())
# Two different things: the id as the event carries it, which is what a
# recorded row keeps, and the live cascade it belongs to — which a batch
# run has none of, since nothing here started one for it.
run_id = str(event.get("run") or "")[:64]
run = self._runs.get(run_id)
if kind == "node_executed":
bucket = self._bucket(event)
bucket["executions"] += 1
bucket["messages"] += int(event.get("outputs") or 0)
duration = float(event.get("duration_ms") or 0.0)
bucket["duration_sum_ms"] += duration
bucket["duration_max_ms"] = max(bucket["duration_max_ms"], duration)
if run is not None:
run["nodes"] += 1
return
if kind == "work_latency":
bucket = self._bucket(event)
lag = float(event.get("lag_ms") or 0.0)
bucket["lag_sum_ms"] += lag
bucket["lag_max_ms"] = max(bucket["lag_max_ms"], lag)
bucket["items"] += 1
return
if kind == "node_log":
# Held for the node_error that follows it from the same thread.
if event.get("level") == "error":
key = (str(event.get("flow") or ""), str(event.get("node") or ""))
self._tracebacks[key] = (ts, str(event.get("text") or "")[:DETAIL_CAP])
return
if kind == "node_error":
self._bucket(event)["errors"] += 1
if run is not None:
run["errors"] += 1
key = (str(event.get("flow") or ""), str(event.get("node") or ""))
traceback = self._tracebacks.pop(key, (0.0, ""))[1]
error = str(event.get("error") or "")
self._pending.append(
EngineEvent(
ts=datetime.fromtimestamp(ts, UTC),
type="node_error",
flow=str(event.get("flow") or ""),
node=str(event.get("node") or ""),
detail=(f"{error}\n{traceback}" if traceback else error)[
:DETAIL_CAP
],
run=run_id,
)
)
return
if kind == "cascade_started":
self._start_run(event, ts)
return
if kind == "cascade_finished":
if run is not None:
run["finished_at"] = datetime.fromtimestamp(ts, UTC)
run["duration_ms"] = round((ts - run["started_ts"]) * 1000, 2)
run["status"] = "error" if run["errors"] else "ok"
return
if kind == "node_health":
if event.get("health") == "down":
self._pending.append(
EngineEvent(
ts=datetime.fromtimestamp(ts, UTC),
type="node_health",
flow=str(event.get("flow") or ""),
node=str(event.get("node") or ""),
detail=_detail(event) or "Reported itself down.",
run=run_id,
)
)
return
if kind == "audit":
self._pending.append(
EngineEvent(
ts=datetime.fromtimestamp(ts, UTC),
type="audit",
flow=str(event.get("flow") or ""),
detail=str(event.get("action") or ""),
actor=str(event.get("user") or ""),
)
)
return
if kind in RECORDED:
self._pending.append(
EngineEvent(
ts=datetime.fromtimestamp(ts, UTC),
type=kind,
flow=str(event.get("flow") or ""),
node=str(event.get("node") or event.get("task") or ""),
detail=_detail(event),
run=run_id,
)
)
def _start_run(self, event: dict[str, Any], ts: float) -> None:
run_id = str(event.get("run") or "")
if not run_id:
return
existing = self._runs.get(run_id)
if existing is not None:
# A redelivery of the same item: one run, tried again.
existing["deliveries"] = int(event.get("deliveries") or 1)
existing["status"] = "running"
existing["finished_at"] = None
return
self._runs[run_id] = {
"id": run_id,
"flow": str(event.get("flow") or "")[:NAME_MAX],
"source": str(event.get("cause") or ""),
"started_ts": ts,
"started_at": datetime.fromtimestamp(ts, UTC),
"finished_at": None,
"status": "running",
"nodes": 0,
"errors": 0,
"duration_ms": 0.0,
"deliveries": int(event.get("deliveries") or 1),
}
# -------------------------------------------------------------------------
# Writing
# -------------------------------------------------------------------------
async def flush(self) -> None:
buckets, self._buckets = self._buckets, {}
pending, self._pending = self._pending, []
# Open runs stay in memory: their counts are still growing, and the row
# is written from the whole record each time rather than in deltas.
runs = list(self._runs.values())
prune = time.monotonic() - self._last_prune >= PRUNE_INTERVAL_S
if not (buckets or pending or runs or prune):
return
try:
await asyncio.to_thread(self._write, buckets, pending, runs, prune)
except Exception:
logger.exception("Could not write engine metrics")
self._hold(buckets, pending)
return
if prune:
self._last_prune = time.monotonic()
cutoff = time.time() - RUN_STALE_S
for run_id, run in list(self._runs.items()):
if run["status"] != "running" or run["started_ts"] < cutoff:
del self._runs[run_id]
# Held tracebacks survive the flush: the log and the failure it belongs
# to are two events, and a flush can fall between them. One per node,
# each replaced by that node's next failure — and dropped once it is
# clear the failure it was waiting for is never coming.
for key, (held, _) in list(self._tracebacks.items()):
if held < cutoff:
del self._tracebacks[key]
def _hold(
self,
buckets: dict[tuple[str, str, int], dict[str, float]],
pending: list[EngineEvent],
) -> None:
"""Take a batch the database refused back, rather than losing it.
These are the audit trail and the failures with their tracebacks — the
rows nobody can reconstruct afterwards. The batch goes in front of what
arrived since, so what a long outage drops is the oldest.
"""
for key, agg in self._buckets.items():
held = buckets.get(key)
if held is None:
buckets[key] = agg
continue
for name in SUMMED:
held[name] += agg[name]
for name in MAXIMA:
held[name] = max(held[name], agg[name])
self._buckets = buckets
# A failed commit puts the rows back to unsaved. One that got as far as
# being handed an id keeps it, and the sequence has already moved past
# it, so adding them to the next session inserts them cleanly.
self._pending[:0] = pending
for key in list(self._buckets)[: max(0, len(self._buckets) - HOLD_MAX)]:
del self._buckets[key]
del self._pending[: max(0, len(self._pending) - HOLD_MAX)]
def _write(
self,
buckets: dict[tuple[str, str, int], dict[str, float]],
pending: list[EngineEvent],
runs: list[dict[str, Any]],
prune: bool,
) -> None:
with Session(engine) as session:
for (flow, node, minute), agg in buckets.items():
statement = insert(MetricBucket).values(
flow=flow,
node=node,
bucket=datetime.fromtimestamp(minute, UTC),
**agg,
)
# The same minute is written several times, so the counters add
# and the maxima take whichever is larger. Columns are read by
# subscript: `excluded.items` is the collection's own method.
new = statement.excluded
session.execute(
statement.on_conflict_do_update(
index_elements=["flow", "node", "bucket"],
set_={
name: col(getattr(MetricBucket, name)) + new[name]
for name in SUMMED
}
| {
# `max` of two values, not the aggregate: SQLite's
# scalar form, which is what `greatest` is elsewhere.
name: func.max(col(getattr(MetricBucket, name)), new[name])
for name in MAXIMA
},
)
)
for run in runs:
values = {k: v for k, v in run.items() if k != "started_ts"}
statement = insert(FlowRun).values(**values)
session.execute(
statement.on_conflict_do_update(
index_elements=["id"],
set_={
key: statement.excluded[key]
for key in values
if key != "id"
},
)
)
session.add_all(pending)
if prune:
self._prune(session)
session.commit()
def _prune(self, session: Session) -> None:
now = datetime.now(UTC)
cutoff = now - timedelta(days=settings.OBS_RETENTION_DAYS)
session.execute(delete(MetricBucket).where(col(MetricBucket.bucket) < cutoff))
session.execute(delete(EngineEvent).where(col(EngineEvent.ts) < cutoff))
session.execute(delete(FlowRun).where(col(FlowRun.started_at) < cutoff))
# A run still open long after it started did not finish; saying so is
# more honest than leaving it running forever.
session.execute(
update(FlowRun)
.where(
col(FlowRun.status) == "running",
col(FlowRun.started_at) < now - timedelta(seconds=RUN_STALE_S),
)
.values(status="abandoned", finished_at=now)
)