Files
app/backend/scripts/bench_engine.py
T

507 lines
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Python

#!/usr/bin/env python
"""Engine throughput bench: what a message costs, in work and in time.
`bench_startup.py` times submitting a run; this times the live path — a value
arriving at a subscriber and reaching everything downstream of it. It builds a
pipeline and an execution service in this process, so there is no HTTP, no
container and no browser between the measurement and the engine.
Four scenarios, each answering a different question:
``throttle``
What does a rate-limited port cost? A source publishes through relays
while incoming readings exceed its publication rate.
Reports cascades enqueued, node executions and bus events per injection —
the numbers, not the wall clock, are the point.
``relay``
The same, with the *source* unlimited: the cascade really is owed, and
what the relays hold back is what the node reading them should not be
woken for.
``throughput``
How many messages a second, and how late is the last node? A relay chain,
driven until the queue drains, reporting end-to-end latency percentiles.
``fanout``
One source into many consumers: the scheduler's own overhead per wave.
Run against the memory backends by default; ``--redis`` points state and queue
at a real Redis, which is what the engine runs on and where the round trips
this is meant to expose actually happen.
"""
from __future__ import annotations
import argparse
import cProfile
import json
import logging
import pstats
import statistics
import sys
import threading
import time
from collections.abc import Callable
from dataclasses import dataclass, field
from typing import Any
from fluksio.flow.events import EventBus
from fluksio.flow.executor import ExecutionService
from fluksio.flow.messages import DType, MessageSpec
from fluksio.flow.nodes import Node
from fluksio.flow.pipeline import Pipeline
from fluksio.flow.queue import MemoryWorkQueue, RedisWorkQueue, WorkQueue
from fluksio.flow.state import MemoryState, RedisState, StateBackend
log = logging.getLogger("bench")
FLOW = "bench"
# -----------------------------------------------------------------------------
# Counting what the engine did
# -----------------------------------------------------------------------------
@dataclass
class Counters:
"""What one scenario cost, counted rather than timed."""
executions: int = 0
events: int = 0
by_event: dict[str, int] = field(default_factory=dict)
#: inject -> when the last node downstream of it finished, in ms.
latencies: list[float] = field(default_factory=list)
def count(self, event: dict[str, Any]) -> None:
kind = str(event.get("type", ""))
self.events += 1
self.by_event[kind] = self.by_event.get(kind, 0) + 1
class CountingBus(EventBus):
"""The real bus, with a tally beside it.
Subclassed rather than mocked: the cost of publishing — the queue per
subscriber, the drop-oldest — is part of what is being measured.
"""
def __init__(self, counters: Counters) -> None:
super().__init__()
self._counters = counters
def publish(self, event: dict[str, Any]) -> None:
self._counters.count(event)
super().publish(event)
# -----------------------------------------------------------------------------
# Building graphs
# -----------------------------------------------------------------------------
def spec(name: str, interval: float = 0.0) -> MessageSpec:
return MessageSpec(name=name, dtype=DType.FLOAT, interval=interval)
def node(
node_id: str,
f: Callable[..., Any],
requires: list[MessageSpec] | None = None,
provides: list[MessageSpec] | None = None,
) -> Node:
n = Node(f=f, requires=requires or [], provides=provides or [], name=node_id)
n.assign_flow(FLOW, node_id)
return n
def relay(
node_id: str, src: str, dst: str, interval: float, counters: Counters
) -> Node:
"""A relay node that republishes its input.
``src`` and ``dst`` are bare port names: the pipeline qualifies them with
the flow, and the node function only ever sees ports.
"""
def body(**kwargs: Any) -> dict[str, Any]:
counters.executions += 1
return {dst: kwargs[src]}
return node(
node_id,
body,
requires=[spec(src)],
provides=[spec(dst, interval=interval)],
)
# -----------------------------------------------------------------------------
# Harness
# -----------------------------------------------------------------------------
class Engine:
"""A pipeline and the service that drains its queue, as the app wires them."""
def __init__(self, nodes: list[Node], redis_host: str, counters: Counters) -> None:
self.counters = counters
self.bus = CountingBus(counters)
self.state: StateBackend
self.queue: WorkQueue
if redis_host:
# A namespace of its own, so a bench never touches a live engine's
# state or its stream.
self.state = RedisState(host=redis_host, namespace="bench")
self.queue = RedisWorkQueue(host=redis_host, namespace="benchq")
self.state.clear()
else:
self.state = MemoryState()
self.queue = MemoryWorkQueue()
self.service = ExecutionService(self.queue, max_workers=4, events=self.bus)
self.pipeline = Pipeline(
nodes=nodes,
state=self.state,
events=self.bus,
work_queue=self.queue,
node_pool=self.service.node_pool,
)
self.service.bind(self.pipeline)
def start(self) -> None:
self.service.start()
def stop(self) -> None:
self.service.stop()
def deliver(self, source: Node, outputs: dict[str, Any]) -> None:
"""Inject one value and run every cascade it owes, in this thread.
The counting scenarios drive the queue by hand rather than starting
the consumer: injecting flat out means five hundred messages land
before the first cascade writes the timestamp its window is measured
from, so every one of them looks due and the thing being counted never
happens. A house sends three readings a second into an engine that
finishes a cascade in four milliseconds, which is this.
"""
source.inject(outputs)
while True:
self.queue.move_due(0.0)
items = self.queue.claim(16, 1)
if not items:
return
for item in items:
self.service._run_item(item)
self.queue.ack(item)
def drain(self, timeout: float = 60.0) -> bool:
"""Wait for the queue to go quiet. False means it never did.
Asks the backlog rather than the whole of ``stats()``: the health
summary's version costs four round trips, and polling it every twenty
milliseconds competes with the engine for the connection it is
supposedly measuring.
Delayed items are not waited for: a rate-limit flush is due a whole
window from now, and the scenario is over long before that.
"""
deadline = time.monotonic() + timeout
quiet_since = 0.0
while time.monotonic() < deadline:
busy = self.service.inflight or self.queue.backlog()
if not busy:
# Two consecutive quiet reads: a cascade between claim and ack
# shows as neither.
if quiet_since and time.monotonic() - quiet_since > 0.15:
return True
quiet_since = quiet_since or time.monotonic()
else:
quiet_since = 0.0
time.sleep(0.02)
return False
def percentile(values: list[float], p: float) -> float:
if not values:
return 0.0
ordered = sorted(values)
idx = min(len(ordered) - 1, int(round(p / 100.0 * (len(ordered) - 1))))
return ordered[idx]
# -----------------------------------------------------------------------------
# Scenarios
# -----------------------------------------------------------------------------
def scenario_throttle(args: argparse.Namespace) -> dict[str, Any]:
"""A rate-limited source behind relays, driven far faster than its window.
Counts the work performed when rapid inputs are held by a publication
interval. Relay count and interval come from the benchmark arguments.
"""
counters = Counters()
source = node(
"source",
lambda params: None,
provides=[spec("raw", interval=args.window)],
)
nodes = [source]
for i in range(args.relays):
nodes.append(relay(f"relay{i}", "raw", f"out{i}", args.window, counters))
engine = Engine(nodes, args.redis, counters)
try:
started = time.perf_counter()
for i in range(args.messages):
engine.deliver(source, {"raw": float(i)})
elapsed = time.perf_counter() - started
finally:
engine.stop()
return {
"scenario": "throttle",
"messages": args.messages,
"relays": args.relays,
"window_s": args.window,
"elapsed_s": round(elapsed, 3),
# The three numbers the bug is about.
"cascades_started": counters.by_event.get("cascade_started", 0),
"node_executions": counters.executions,
"bus_events": counters.events,
"published": counters.by_event.get("message_value", 0),
"per_message": {
"cascades": round(
counters.by_event.get("cascade_started", 0) / args.messages, 3
),
"executions": round(counters.executions / args.messages, 3),
"events": round(counters.events / args.messages, 3),
},
}
def scenario_relay(args: argparse.Namespace) -> dict[str, Any]:
"""An *unlimited* source into limited relays, and one node reading them all.
Each input starts a cascade, but rate-limited relay outputs should wake
the consumer only when they publish a new value.
"""
counters = Counters()
source = node("source", lambda params: None, provides=[spec("raw")])
nodes = [source]
for i in range(args.relays):
nodes.append(relay(f"relay{i}", "raw", f"out{i}", args.window, counters))
ports = [f"out{i}" for i in range(args.relays)]
def watch(**kwargs: Any) -> dict[str, Any]:
counters.executions += 1
return {"total": sum(kwargs[p] for p in ports)}
nodes.append(
node(
"watch",
watch,
requires=[spec(p) for p in ports],
provides=[spec("total")],
)
)
engine = Engine(nodes, args.redis, counters)
try:
started = time.perf_counter()
for i in range(args.messages):
engine.deliver(source, {"raw": float(i)})
elapsed = time.perf_counter() - started
finally:
engine.stop()
return {
"scenario": "relay",
"messages": args.messages,
"relays": args.relays,
"window_s": args.window,
"elapsed_s": round(elapsed, 3),
"cascades_started": counters.by_event.get("cascade_started", 0),
"node_executions": counters.executions,
"bus_events": counters.events,
"published": counters.by_event.get("message_value", 0),
"per_message": {
"executions": round(counters.executions / args.messages, 3),
"events": round(counters.events / args.messages, 3),
},
}
def scenario_throughput(args: argparse.Namespace) -> dict[str, Any]:
"""A relay chain, driven flat out: messages a second, and how late the tail is."""
counters = Counters()
starts: dict[float, float] = {}
lock = threading.Lock()
source = node("source", lambda params: None, provides=[spec("v0")])
nodes = [source]
for i in range(args.depth):
nodes.append(relay(f"relay{i}", f"v{i}", f"v{i + 1}", 0.0, counters))
# The last link records how long the value took to walk the whole chain.
last_port = f"v{args.depth}"
def sink(**kwargs: Any) -> None:
counters.executions += 1
value = kwargs[last_port]
with lock:
sent = starts.get(value)
if sent is not None:
counters.latencies.append((time.perf_counter() - sent) * 1000)
nodes.append(node("sink", sink, requires=[spec(last_port)]))
engine = Engine(nodes, args.redis, counters)
engine.start()
try:
started = time.perf_counter()
for i in range(args.messages):
value = float(i)
with lock:
starts[value] = time.perf_counter()
source.inject({"v0": value})
drained = engine.drain(args.drain_timeout)
elapsed = time.perf_counter() - started
finally:
engine.stop()
delivered = len(counters.latencies)
return {
"scenario": "throughput",
"messages": args.messages,
"depth": args.depth,
"drained": drained,
"elapsed_s": round(elapsed, 3),
"msgs_per_s": round(args.messages / elapsed, 1) if elapsed else 0.0,
"delivered": delivered,
"latency_ms": {
"p50": round(percentile(counters.latencies, 50), 2),
"p95": round(percentile(counters.latencies, 95), 2),
"max": round(max(counters.latencies), 2) if counters.latencies else 0.0,
"mean": round(statistics.fmean(counters.latencies), 2)
if delivered
else 0.0,
},
"node_executions": counters.executions,
"bus_events": counters.events,
}
def scenario_fanout(args: argparse.Namespace) -> dict[str, Any]:
"""One source into many consumers: what the wave scheduler costs per node."""
counters = Counters()
source = node("source", lambda params: None, provides=[spec("raw")])
nodes = [source]
for i in range(args.width):
nodes.append(relay(f"leaf{i}", "raw", f"out{i}", 0.0, counters))
engine = Engine(nodes, args.redis, counters)
engine.start()
try:
started = time.perf_counter()
for i in range(args.messages):
source.inject({"raw": float(i)})
drained = engine.drain(args.drain_timeout)
elapsed = time.perf_counter() - started
finally:
engine.stop()
return {
"scenario": "fanout",
"messages": args.messages,
"width": args.width,
"drained": drained,
"elapsed_s": round(elapsed, 3),
"msgs_per_s": round(args.messages / elapsed, 1) if elapsed else 0.0,
"node_executions": counters.executions,
"bus_events": counters.events,
}
SCENARIOS: dict[str, Callable[[argparse.Namespace], dict[str, Any]]] = {
"throttle": scenario_throttle,
"relay": scenario_relay,
"throughput": scenario_throughput,
"fanout": scenario_fanout,
}
# -----------------------------------------------------------------------------
# Entry point
# -----------------------------------------------------------------------------
def report(result: dict[str, Any]) -> None:
name = result.pop("scenario")
log.info("\n=== %s ===", name)
for key, value in result.items():
if isinstance(value, dict):
inner = " ".join(f"{k}={v}" for k, v in value.items())
log.info(" %-18s %s", key, inner)
else:
log.info(" %-18s %s", key, value)
def main() -> int:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument(
"--scenario",
choices=[*SCENARIOS, "all"],
default="all",
help="Which scenario to run (default: all).",
)
parser.add_argument("--messages", type=int, default=500)
parser.add_argument("--relays", type=int, default=7, help="throttle: relay count")
parser.add_argument("--window", type=float, default=15.0, help="throttle: interval")
parser.add_argument("--depth", type=int, default=5, help="throughput: chain length")
parser.add_argument("--width", type=int, default=20, help="fanout: consumer count")
parser.add_argument(
"--redis",
nargs="?",
const="localhost",
default="",
metavar="HOST",
help="Run against a real Redis (namespaces bench/benchq) rather than memory.",
)
parser.add_argument("--drain-timeout", type=float, default=60.0)
parser.add_argument("--profile", action="store_true", help="cProfile, top 25.")
parser.add_argument("--json", action="store_true", help="Machine-readable output.")
args = parser.parse_args()
logging.basicConfig(level=logging.INFO, format="%(message)s", stream=sys.stdout)
names = list(SCENARIOS) if args.scenario == "all" else [args.scenario]
profiler = cProfile.Profile() if args.profile else None
if profiler:
profiler.enable()
results = [SCENARIOS[name](args) for name in names]
if profiler:
profiler.disable()
if args.json:
log.info(json.dumps(results, indent=2))
else:
for result in results:
report(dict(result))
if profiler:
log.info("\n=== profile (cumulative, top 25) ===")
pstats.Stats(profiler, stream=sys.stdout).sort_stats("cumulative").print_stats(
25
)
return 0
if __name__ == "__main__":
raise SystemExit(main())