bengal-pounce 0.6.0

Python ASGI server for production apps, streaming responses, and free-threaded Python

=^..^= Pounce

Pure Python ASGI server. 7x faster HTTP parsing. True thread parallelism on Python 3.14t.

import pounce

pounce.run("myapp:app")

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What is Pounce?

Pounce is a Python ASGI server for Python 3.14+, with a worker model designed for free-threaded Python 3.14t. It runs standard ASGI applications, supports streaming responses, and gives you a clear upgrade path from process-based servers such as Uvicorn.

Pounce's built-in HTTP/1.1 parser runs at ~3 us per request (7x faster than h11), its frozen configuration eliminates all locking overhead, and its rolling reload spawns new workers while draining old ones — zero dropped requests.

On Python 3.14t, worker threads share one interpreter and one copy of your app. On GIL builds, Pounce falls back to multi-process workers automatically.

Why people pick it:

• ASGI-first — Runs standard ASGI apps with CLI and programmatic entry points
• Free-threading native — True thread parallelism with frozen immutable config (zero locks)
• 7x faster parsing — Built-in HTTP/1.1 parser (~3 us/req) with full request smuggling protection
• Four protocols — HTTP/1.1, HTTP/2, HTTP/3 (QUIC), and WebSocket (including WS over H2)
• Zero-downtime reload — Rolling restart with generational worker swap, no dropped requests
• Observable — Typed lifecycle events, Prometheus metrics, OpenTelemetry, Server-Timing headers
• Batteries included — TLS, compression, static files, middleware, rate limiting, observability
• Migration path — Familiar CLI for teams moving from Uvicorn-style deployments

Use Pounce For

• Serving ASGI apps — Tunable workers, TLS, graceful shutdown, and deployment controls
• Free-threaded Python deployments — Shared-memory worker threads on Python 3.14t
• Streaming workloads — Server-sent events, streamed HTML, and token-by-token responses
• Teams migrating from Uvicorn — Similar CLI shape with a different worker model

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Framework Compatibility

Tested in CI with 48 integration tests across every major ASGI framework:

Framework	Status	Features Verified
FastAPI 0.135+	Full	Routing, Pydantic validation, dependency injection, middleware, exception handlers, lifespan, WebSocket, streaming, OpenAPI schema
Starlette 1.0+	Full	Routing, BaseHTTPMiddleware, lifespan with state, streaming, WebSocket, background tasks, exception handlers
Django 6.0+	Full	Async views, URL routing, path params, JSON body, query params, middleware, error handling
Litestar 2.21+	Core	Routing, dependency injection, middleware, lifespan, streaming, exception handlers. WebSocket: known routing issue

Pounce achieves compatibility through correct ASGI 3.0 implementation — no framework-specific code or workarounds.

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Performance

Pounce matches uvicorn on throughput — pure Python, no C extensions.

Scenario	Pounce	Uvicorn	Notes
1 worker	~7.2k req/s	~6.5k req/s	Async event loop, h11 parser
4 workers	~16k req/s	~17k req/s	Threads (pounce) vs processes (uvicorn)

Measured with wrk -t4 -c100 -d10s on macOS Apple Silicon, plain-text "hello world" ASGI app, Python 3.14t.

Run pounce bench --workers 4 --compare to reproduce on your machine.

Key optimizations in the sync worker path:

• Fast HTTP/1.1 parser — Direct bytes parsing (~3 µs/req) replaces h11 (~22 µs/req) with full safety checks (method validation, header size limits, request smuggling detection)
• Keep-alive connections — Connection reuse eliminates TCP handshake overhead
• Shared socket distribution — Single accept queue for thread workers avoids macOS SO_REUSEPORT limitations

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Installation

pip install bengal-pounce

Requires Python 3.14+

Optional extras:

pip install bengal-pounce[h2]     # HTTP/2 stream multiplexing
pip install bengal-pounce[ws]     # WebSocket via wsproto
pip install bengal-pounce[tls]    # TLS with truststore
pip install bengal-pounce[h3]     # HTTP/3 (QUIC/UDP, requires TLS)
pip install bengal-pounce[full]   # All protocol extras

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Quick Start

Usage	Command
Programmatic	pounce.run("myapp:app")
CLI	pounce myapp:app
Multi-worker	pounce myapp:app --workers 4
TLS	pounce myapp:app --ssl-certfile cert.pem --ssl-keyfile key.pem
HTTP/3	pounce myapp:app --http3 --ssl-certfile cert.pem --ssl-keyfile key.pem
Dev reload	pounce myapp:app --reload
App factory	pounce myapp:create_app()
Testing	with TestServer(app) as server: ...

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Features

Feature	Description	Docs
Deployment	Production workers, compression, observability, and shutdown behavior	Deployment →
Migration	Move from Uvicorn with similar CLI concepts	Migrate from Uvicorn →
HTTP/1.1	h11 (async) + fast built-in parser (sync)	HTTP/1.1 →
HTTP/2	Stream multiplexing via h2	HTTP/2 →
HTTP/3	QUIC/UDP via bengal-zoomies (requires TLS)	HTTP/3 →
WebSocket	Full RFC 6455 via wsproto (including WS over H2)	WebSocket →
Static Files	Pre-compressed files, ETags, range requests	Static Files →
Middleware	ASGI3 middleware stack support	Middleware →
OpenTelemetry	Native distributed tracing (OTLP)	OpenTelemetry →
Lifecycle Logging	Structured JSON event logging	Logging →
Graceful Shutdown	Kubernetes-ready connection draining	Shutdown →
Dev Error Pages	Rich tracebacks with syntax highlighting	Errors →
TLS	SSL with truststore integration	TLS →
Compression	zstd (stdlib PEP 784) + gzip + WS compression	Compression →
Workers	Auto-detect: threads (3.14t) or processes (GIL)	Workers →
Auto Reload	Graceful restart on file changes	Reload →
Rate Limiting	Per-IP token bucket with 429 responses	Rate Limiting →
Request Queueing	Bounded queue with 503 load shedding	Request Queueing →
Prometheus	Built-in /metrics endpoint	Metrics →
Sentry	Error tracking and performance monitoring	Sentry →
Testing	TestServer + pytest fixture for integration tests	Testing →
Benchmarking	Built-in pounce bench command with comparative analysis	Bench →
Lifecycle Events	Public API for typed connection/request events	API →

📚 Full documentation: lbliii.github.io/pounce | Complete Feature List →

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Usage

Programmatic Configuration — Full control from Python

import pounce

pounce.run(
    "myapp:app",
    host="0.0.0.0",
    port=8000,
    workers=4,
)

How It Works — Adaptive worker model

On Python 3.14t (free-threading): workers are threads. One process, N threads, each with its own asyncio event loop. Shared memory, no fork overhead, no IPC.

On GIL builds: workers are processes. Same API, same config. The supervisor detects the runtime via sys._is_gil_enabled() and adapts automatically.

A request flows through: socket accept -> protocol parser -> ASGI scope construction -> app(scope, receive, send) -> response serialization -> socket write. Async workers use h11; sync workers use a fast built-in parser for lower latency.

Protocol Extras — Install only what you need

Protocol	Backend	Install
HTTP/1.1	h11 (async) / fast built-in parser (sync)	built-in
HTTP/2	h2 (stream multiplexing, priority signals)	pounce[h2]
WebSocket	wsproto (including WS over H2)	pounce[ws]
TLS	stdlib ssl + truststore	pounce[tls]
All	Everything above	pounce[full]

Compression uses Python 3.14's stdlib compression.zstd — zero external dependencies.

Testing — Real server for integration tests

from pounce.testing import TestServer
import httpx

def test_homepage(my_app):
    with TestServer(my_app) as server:
        resp = httpx.get(f"{server.url}/")
        assert resp.status_code == 200

The pounce_server pytest fixture is auto-registered when pounce is installed:

def test_api(pounce_server, my_app):
    server = pounce_server(my_app)
    resp = httpx.get(f"{server.url}/health")
    assert resp.status_code == 200

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Key Ideas

• Free-threading first. Threads, not processes. One interpreter, N event loops, shared immutable state. On GIL builds, falls back to multi-process automatically.
• Pure Python. No Rust, no C extensions in the server core. Debuggable, hackable, readable.
• Typed end-to-end. Frozen config, typed ASGI definitions, zero type: ignore comments.
• One dependency. h11 for HTTP/1.1 parsing. Everything else is optional.
• Observable by design. Lifecycle events are public API — from pounce import BufferedCollector, ResponseCompleted. Frameworks build dashboards on typed events, not log parsing.
• Framework tested. Verified against FastAPI, Starlette, Django, and Litestar with 48 integration tests.
• Batteries included. Static files, middleware, rate limiting, request queueing, Prometheus metrics, Sentry, and OpenTelemetry — all built in, all optional.

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Documentation

📚 lbliii.github.io/pounce

Section	Description
Get Started	Installation and quickstart
Protocols	HTTP/1.1, HTTP/2, WebSocket
Configuration	Server config, TLS, CLI
Deployment	Workers, compression, production
Extending	ASGI bridge, custom protocols
Tutorials	Uvicorn migration guide
Troubleshooting	Common issues and fixes
Reference	API documentation
About	Architecture, performance, FAQ

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Development

git clone https://github.com/lbliii/pounce.git
cd pounce
uv sync --group dev
pytest

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The Bengal Ecosystem

A structured reactive stack — every layer written in pure Python for 3.14t free-threading.

ᓚᘏᗢ	Bengal	Static site generator	Docs
∿∿	Purr	Content runtime	—
⌁⌁	Chirp	Web framework	Docs
=^..^=	Pounce	ASGI server ← You are here	Docs
)彡	Kida	Template engine	Docs
ฅᨐฅ	Patitas	Markdown parser	Docs
⌾⌾⌾	Rosettes	Syntax highlighter	Docs

Python-native. Free-threading ready. No npm required.

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License

MIT