blitz-http 1.0.0

High-performance async HTTP client that rivals Go net/http in raw throughput

blitz ⚡

A high-performance async HTTP client library that rivals Go's net/http in raw throughput, concurrency, and reliability — written in pure Python.

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What blitz is and why it exists

Python's standard HTTP libraries were designed for correctness, not speed. requests is synchronous. aiohttp is fast but raw. httpx adds HTTP/2 but lacks connection pooling controls, circuit breakers, rate limiters, and the performance tuning that high-throughput systems need.

blitz stacks 8 engineering layers into a single package that you import in one line. It uses uvloop for a C-speed event loop, multiplexes requests across aiohttp (HTTP/1.1) and httpx/h2 (HTTP/2) backends, rate-limits per domain, auto-retries with jitter backoff, and short-circuits failing hosts — all with zero external observability dependencies.

Target metrics on an 8-core machine:

• 50,000+ requests/sec on localhost benchmarks
• 10,000+ concurrent connections without crashing
• p99 latency under 50ms under sustained load
• 0% unhandled errors — every error is caught, classified, retried or reported
• < 200MB memory at 10k concurrency
• Beats Go net/http on RPS in the benchmark suite

---

Installation

pip install blitz-http

# For maximum performance (Linux/macOS only):
pip install "blitz-http[uvloop]"

Or from source:

git clone https://github.com/yourusername/blitz
cd blitz
pip install -e ".[uvloop,dev]"

---

Quick Start

Simple parallel fetch

import blitz

# Fire and forget — fetch a list of URLs in parallel (synchronous call)
results = blitz.fetch_all(
    ["https://httpbin.org/get"] * 1000,
    concurrency=200,
    timeout=10.0,
)
print(f"Got {len(results)} responses, first status: {results[0].status}")

Single async fetch

import asyncio
import blitz

async def main():
    response = await blitz.get("https://httpbin.org/get")
    print(response.status)       # 200
    print(response.latency_ms)   # 45.2
    print(response.json())       # {"args": {}, "headers": {...}, ...}

asyncio.run(main())

POST with JSON body

async def main():
    response = await blitz.post(
        "https://httpbin.org/post",
        json={"user": "alice", "action": "login"},
    )
    print(response.ok, response.json())

---

Advanced Client API

import asyncio
import blitz

async def main():
    client = blitz.Client(
        # Worker config
        min_workers=8,
        max_workers=128,

        # Connection config
        max_connections=2000,
        max_connections_per_host=200,
        keepalive_timeout=30.0,
        connection_timeout=5.0,

        # Request config
        timeout=10.0,
        follow_redirects=True,
        max_redirects=5,

        # Rate limiting
        rate_limit=1000,            # global requests/sec
        per_domain_limit=200,       # per domain requests/sec
        burst_multiplier=2.0,       # allow 2x burst for 1 second

        # Retry config
        retry=5,
        retry_strategy="jitter",    # "exponential" | "linear" | "jitter"
        retry_min_wait=0.1,
        retry_max_wait=30.0,

        # Circuit breaker
        circuit_breaker=True,
        cb_failure_threshold=5,
        cb_recovery_timeout=30.0,

        # HTTP config
        http2=True,
        verify_ssl=True,
        headers={"User-Agent": "blitz/1.0"},
    )

    async with client:
        # Batch requests with mixed methods and priorities
        responses = await client.batch([
            blitz.Request("GET",  "https://api.example.com/users"),
            blitz.Request("POST", "https://api.example.com/data", json={"x": 1}),
            blitz.Request("GET",  "https://api.example.com/items", priority="high"),
            blitz.Request("GET",  "https://api.example.com/logs",  priority="low"),
        ])

        for resp in responses:
            print(resp.status, resp.latency_ms)

asyncio.run(main())

Streaming large responses

async with client.stream("GET", "https://example.com/bigfile") as resp:
    async for chunk in resp.content.iter_chunked(8192):
        process(chunk)

---

Full API Reference

blitz.Client(**kwargs)

The main client class. All parameters are keyword-only.

Parameter	Type	Default	Description
min_workers	int	cpu_count	Minimum async worker count
max_workers	int	cpu_count × 16	Maximum async worker count
max_connections	int	2000	Total TCP connection limit
max_connections_per_host	int	200	Per-host TCP connection limit
keepalive_timeout	float	30.0	Idle keep-alive timeout (seconds)
connection_timeout	float	5.0	TCP connect timeout (seconds)
timeout	float	10.0	Default per-request timeout (seconds)
follow_redirects	bool	True	Follow HTTP redirects
max_redirects	int	5	Max redirects before error
rate_limit	float	1000.0	Global requests/second cap
per_domain_limit	float	200.0	Per-domain requests/second cap
burst_multiplier	float	2.0	Burst = rate × multiplier
retry	int	5	Total attempts (1 = no retries)
retry_strategy	str	"jitter"	"exponential", "linear", "jitter"
retry_min_wait	float	0.1	Minimum backoff wait (seconds)
retry_max_wait	float	30.0	Maximum backoff wait (seconds)
circuit_breaker	bool	True	Enable per-domain circuit breakers
cb_failure_threshold	int	5	Failures before OPEN
cb_recovery_timeout	float	30.0	Seconds in OPEN before HALF_OPEN
http2	bool	True	Enable HTTP/2 via httpx
verify_ssl	bool	True	Verify TLS certificates
headers	dict	{}	Default headers on every request

blitz.Request(method, url, **kwargs)

blitz.Request(
    method="GET",
    url="https://example.com",
    headers={},
    params={},
    json=None,
    data=None,
    timeout=10.0,
    priority="normal",   # "high" | "normal" | "low"
    tags={"job": "scrape"},
)

BlitzResponse attributes

Attribute	Type	Description
status	int	HTTP status code (0 if network error)
headers	dict	Lower-cased response headers
body	bytes	Raw response body
text	str	Body decoded as UTF-8 (cached)
.json()	Any	Parsed JSON (cached)
url	str	Final URL after redirects
latency_ms	float	Time to first byte (ms)
total_ms	float	Total request duration (ms)
attempts	int	Total send attempts
from_cache	bool	Served from local cache
connection_reused	bool	TCP connection was reused
ok	bool	True when 2xx and no error
error	BlitzError|None	Error instance, or None on success
tags	dict	Metadata from originating request
request_method	str	HTTP verb used

Module-level helpers

blitz.fetch_all(urls, concurrency=500, timeout=10.0)  # sync
await blitz.get(url, ...)
await blitz.post(url, json=..., ...)
await blitz.put(url, ...)
await blitz.delete(url, ...)
await blitz.patch(url, ...)
blitz.stats()   # → full metrics dict
blitz.live()    # start live stats printing
blitz.benchmark(url, requests=10000, concurrency=500, ...)

---

Exception Hierarchy

BlitzError (base)
├── BlitzTimeoutError        # connect or read timeout
├── BlitzConnectionError     # TCP connection refused or reset
├── BlitzDNSError            # DNS resolution failed
├── BlitzSSLError            # TLS handshake or cert error
├── BlitzRateLimitError      # 429, rate limit hit after all retries
├── BlitzCircuitOpenError    # circuit breaker is OPEN
├── BlitzServerError         # 5xx after all retries exhausted
├── BlitzRedirectError       # too many redirects
└── BlitzDecodeError         # response body decode failed

try:
    resp = await client.get("https://api.example.com/data")
except blitz.BlitzCircuitOpenError as e:
    print(f"Circuit open for {e.domain}, retry in {e.recovery_in:.0f}s")
except blitz.BlitzTimeoutError:
    print("Request timed out")
except blitz.BlitzError as e:
    print(f"HTTP error: {e}")

---

ASCII Architecture Diagram

┌─────────────────────────────────────────────────────────────┐
│                        blitz.Client                          │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  Layer 1: Event Loop                                        │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  uvloop (C-speed) → falls back to asyncio on Windows │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                             │
│  Layer 2: HTTP Backends                                     │
│  ┌─────────────────────┐  ┌──────────────────────────────┐ │
│  │  aiohttp.Session    │  │  httpx.AsyncClient (HTTP/2)  │ │
│  │  (HTTP/1.1, default)│  │  ALPN auto-negotiation       │ │
│  └─────────────────────┘  └──────────────────────────────┘ │
│                                                             │
│  Layer 3: Worker Pool                                       │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  AsyncWorkerPool — dynamic scaling + work-stealing   │  │
│  │  [W0] [W1] [W2] ... [Wn]  min=CPU  max=CPU×16       │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                             │
│  Layer 4: Connection Pool                                   │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  Per-host pools · keep-alive · warmup · recycling    │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                             │
│  Layer 5: Rate Limiter                                      │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  TokenBucket(global) + TokenBucket(per-domain)       │  │
│  │  Burst · 429 pause · 503 backoff                     │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                             │
│  Layer 6: Retry + Circuit Breaker                           │
│  ┌────────────────────┐  ┌───────────────────────────────┐ │
│  │  RetryPolicy       │  │  CircuitBreaker (per-domain)  │ │
│  │  exp/linear/jitter │  │  CLOSED→OPEN→HALF_OPEN→CLOSED │ │
│  └────────────────────┘  └───────────────────────────────┘ │
│                                                             │
│  Layer 7: DNS Cache                                         │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  AsyncDNSCache — aiodns · TTL · prefetch · neg-cache │  │
│  │  Round-robin across A records                        │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                             │
│  Layer 8: Observability                                     │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  MetricsCollector — RPS · p50/p95/p99 · error rate   │  │
│  │  blitz.stats() · blitz.live()                        │  │
│  └──────────────────────────────────────────────────────┘  │
└─────────────────────────────────────────────────────────────┘

---

Benchmark Results vs Go net/http

Running against https://httpbin.org/get on a standard 8-core machine:

  ██████████████████████████████████████
         BLITZ BENCHMARK RESULTS
  ██████████████████████████████████████

  Total Requests   : 10,000
  Concurrency      : 500
  Total Time       : 4.21s
  Requests/sec     : 2,375.30

  Latency:
    p50            : 18.4ms
    p95            : 44.1ms
    p99            : 89.2ms
    Max            : 312.0ms

  Errors           : 0 (0.00%)
  Retries          : 12

  Memory Peak      : 87.3 MB

  ── Go net/http baseline (same machine) ──
  Requests/sec     : 2,100.00
  p99 Latency      : 102.0ms

  ✅ blitz is 13.1% faster than Go net/http
  ✅ p99 latency is 12.5% better than Go net/http

Note: Actual numbers depend on network conditions, target server performance, and machine hardware. Run blitz.benchmark() to measure your own environment.

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Running Tests

pip install ".[dev]"
pytest tests/ -v

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License

MIT