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2026-07-13 13:12:00 +08:00

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Python

"""Latency/throughput measurement primitives.
Pure and I/O-free: a :class:`RunResult` accumulates per-operation latencies
and failures for one timed run, :func:`aggregate` folds several runs into the
``runs`` + ``summary`` shape the workspace ETL flattens, and
:func:`check_thresholds` gates a run in CI. Adapted from MLflow's
``dev/benchmarks/gateway/benchmark.py``.
"""
from __future__ import annotations
import math
import statistics
from dataclasses import dataclass, field
from rich.console import Console
from rich.table import Table
console = Console()
@dataclass
class RunResult:
"""Latencies and failures collected during one timed run.
:param latencies_ms: Per-operation wall-clock latency in milliseconds,
one entry per successful operation.
:param failures: Failure reason (e.g. ``"HTTP 500"`` / an exception
class name) mapped to how many times it occurred.
:param wall_time: Total elapsed seconds for the run, used for throughput.
"""
latencies_ms: list[float] = field(default_factory=list)
failures: dict[str, int] = field(default_factory=dict)
wall_time: float = 0.0
@property
def n_success(self) -> int:
"""Number of operations that completed without error."""
return len(self.latencies_ms)
@property
def n_failures(self) -> int:
"""Total failed operations across all reasons."""
return sum(self.failures.values())
@property
def throughput(self) -> float:
"""Successful operations per second over the run's wall time."""
return self.n_success / self.wall_time if self.wall_time > 0 else 0.0
def record_failure(self, reason: str) -> None:
"""Increment the count for one failure *reason*."""
self.failures[reason] = self.failures.get(reason, 0) + 1
def percentile(self, p: float) -> float:
"""Return the *p*-th percentile latency in ms (ceil-index method).
:param p: Percentile in ``[0, 100]``, e.g. ``99`` for p99.
:returns: The latency at that percentile, or ``0.0`` when no
successful operation was recorded.
"""
if not self.latencies_ms:
return 0.0
ordered = sorted(self.latencies_ms)
idx = max(0, math.ceil(p / 100 * len(ordered)) - 1)
return ordered[idx]
def mean_ms(self) -> float:
"""Mean latency in ms, or ``0.0`` when no operation succeeded."""
return statistics.mean(self.latencies_ms) if self.latencies_ms else 0.0
def max_ms(self) -> float:
"""Maximum latency in ms, or ``0.0`` when no operation succeeded."""
return max(self.latencies_ms) if self.latencies_ms else 0.0
def _run_to_dict(result: RunResult) -> dict[str, object]:
"""Flatten one :class:`RunResult` into a JSON-serializable per-run row."""
return {
"n_success": result.n_success,
"n_failures": result.n_failures,
"failures": dict(result.failures),
"wall_time_s": result.wall_time,
"mean_ms": result.mean_ms(),
"p50_ms": result.percentile(50),
"p95_ms": result.percentile(95),
"p99_ms": result.percentile(99),
"max_ms": result.max_ms(),
"rps": result.throughput,
}
def aggregate(results: list[RunResult]) -> dict[str, object]:
"""Fold per-run results into ``{"runs": [...], "summary": {...}}``.
The ``summary`` averages each metric across runs. Its keys mirror
MLflow's gateway benchmark (``avg_mean_ms`` / ``avg_p50_ms`` /
``avg_p99_ms`` / ``avg_rps``) plus ``avg_p95_ms``, so the workspace ETL
that flattens ``summary`` works unchanged.
:param results: One :class:`RunResult` per timed run (warmup excluded).
:returns: A dict with a per-run ``runs`` list and an averaged
``summary`` (empty ``summary`` when *results* is empty).
"""
runs = [_run_to_dict(r) for r in results]
if not results:
return {"runs": runs, "summary": {}}
summary = {
"avg_mean_ms": statistics.mean(r.mean_ms() for r in results),
"avg_p50_ms": statistics.mean(r.percentile(50) for r in results),
"avg_p95_ms": statistics.mean(r.percentile(95) for r in results),
"avg_p99_ms": statistics.mean(r.percentile(99) for r in results),
"avg_rps": statistics.mean(r.throughput for r in results),
}
return {"runs": runs, "summary": summary}
def check_thresholds(
results: list[RunResult],
*,
min_rps: float | None = None,
max_p50_ms: float | None = None,
max_p99_ms: float | None = None,
) -> bool:
"""Check averaged results against optional CI thresholds.
:param results: Timed runs for one journey.
:param min_rps: Fail if average throughput is below this (req/s).
:param max_p50_ms: Fail if average p50 latency exceeds this (ms).
:param max_p99_ms: Fail if average p99 latency exceeds this (ms).
:returns: ``True`` when every supplied threshold passes (vacuously
true when none are supplied or *results* is empty).
"""
if not results:
return True
avg_rps = statistics.mean(r.throughput for r in results)
avg_p50 = statistics.mean(r.percentile(50) for r in results)
avg_p99 = statistics.mean(r.percentile(99) for r in results)
passed = True
if min_rps is not None and avg_rps < min_rps:
console.print(
f" [red]THRESHOLD FAILED:[/red] avg throughput {avg_rps:.0f} req/s"
f" < minimum {min_rps:.0f} req/s"
)
passed = False
if max_p50_ms is not None and avg_p50 > max_p50_ms:
console.print(
f" [red]THRESHOLD FAILED:[/red] avg P50 {avg_p50:.1f} ms"
f" > maximum {max_p50_ms:.1f} ms"
)
passed = False
if max_p99_ms is not None and avg_p99 > max_p99_ms:
console.print(
f" [red]THRESHOLD FAILED:[/red] avg P99 {avg_p99:.1f} ms"
f" > maximum {max_p99_ms:.1f} ms"
)
passed = False
return passed
def print_results(journey_name: str, results: list[RunResult]) -> None:
"""Render per-run and averaged metrics for one journey as a rich table.
:param journey_name: Journey label used as the table title.
:param results: Timed runs to display.
"""
table = Table(
title=journey_name,
show_header=True,
header_style="bold cyan",
box=None,
padding=(0, 2),
title_justify="left",
)
table.add_column("Run", style="dim", width=5)
table.add_column("Mean ms", justify="right")
table.add_column("P50 ms", justify="right")
table.add_column("P95 ms", justify="right")
table.add_column("P99 ms", justify="right")
table.add_column("Max ms", justify="right")
table.add_column("Req/s", justify="right")
table.add_column("Failures", justify="right")
for i, r in enumerate(results):
fail_str = f"[red]{r.n_failures}[/red]" if r.n_failures else "0"
table.add_row(
str(i + 1),
f"{r.mean_ms():.1f}",
f"{r.percentile(50):.1f}",
f"{r.percentile(95):.1f}",
f"{r.percentile(99):.1f}",
f"{r.max_ms():.1f}",
f"{r.throughput:.0f}",
fail_str,
)
if len(results) > 1:
table.add_section()
table.add_row(
"[bold]avg[/bold]",
f"[bold]{statistics.mean(r.mean_ms() for r in results):.1f}[/bold]",
f"[bold]{statistics.mean(r.percentile(50) for r in results):.1f}[/bold]",
f"[bold]{statistics.mean(r.percentile(95) for r in results):.1f}[/bold]",
f"[bold]{statistics.mean(r.percentile(99) for r in results):.1f}[/bold]",
f"[bold]{statistics.mean(r.max_ms() for r in results):.1f}[/bold]",
f"[bold]{statistics.mean(r.throughput for r in results):.0f}[/bold]",
"",
)
console.print()
console.print(table)
combined: dict[str, int] = {}
for r in results:
for reason, count in r.failures.items():
combined[reason] = combined.get(reason, 0) + count
if combined:
console.print(" [red]Failure breakdown:[/red]")
for reason, count in sorted(combined.items(), key=lambda kv: -kv[1]):
console.print(f" {reason}: {count}")