aiofastnet

aiofastnet provides drop-in optimized replacements for asyncio's:

• loop.create_connection()
• loop.create_server()
• loop.start_tls()
• loop.sendfile()

If your library or application already uses the asyncio transport/protocol model, aiofastnet lets you keep the same architecture while replacing one of the most expensive layers underneath it.

Benchmark

The benchmark below compares echo round-trips over loopback for TCP and SSL. The exact gains depend on workload, message sizes, CPU, OpenSSL version, and how much of your total runtime is spent in transport/SSL plumbing.

Benchmark source: examples/benchmark.py

In these benchmarks, aiofastnet is up to 2.2x faster than standard asyncio.

Why Use aiofastnet

• Faster hot path. Transport and SSL internals are reimplemented in Cython/C to reduce overhead on long-lived connections.
• Drop-in API. Keep using the standard asyncio transport/protocol model and familiar loop-level networking operations.
• Works with the event loop you already use. aiofastnet works with stock asyncio loops, uvloop, and winloop.
• Particularly strong for SSL-heavy workloads. aiofastnet uses OpenSSL more directly and avoids extra copies in the data path.
• Safer ``write()`` / ``writelines()`` behavior. If the socket cannot accept everything immediately, only bytes and memoryview objects backed by bytes are retained without copying. Other objects, including bytearray and non-bytes exporters, are copied before being queued. Unlike standard asyncio transports, this avoids sending corrupted data if application code modifies the underlying buffer after write() / writelines() returns.
• Better SSL backpressure semantics. Buffer sizes and write limits reflect what is actually queued across the stack.
• Works for library authors. WebSocket, HTTP, RPC, proxy, database, broker, and custom protocol libraries can expose the same API while giving users a faster transport layer.

Quickstart

Install from PyPI:

$ pip install aiofastnet

aiofastnet requires Python 3.9 or greater.

The API mirrors stdlib asyncio. Pass the running loop and use your existing protocol factory:

import asyncio
import aiofastnet

class EchoClientProtocol(asyncio.Protocol):
    def connection_made(self, transport):
        self.transport = transport
        self.transport.write(b"hello")

    def data_received(self, data):
        print("received:", data)
        self.transport.close()

async def main():
    loop = asyncio.get_running_loop()

    transport, protocol = await aiofastnet.create_connection(
        loop,
        EchoClientProtocol,
        "127.0.0.1",
        9000,
    )

    await asyncio.sleep(0.1)

asyncio.run(main())

For servers, replace loop.create_server(...) with aiofastnet.create_server(loop, ...) in the same way.

aiofastnet also exposes start_tls and sendfile:

transport = await aiofastnet.start_tls(
    loop,
    transport,
    protocol,
    ssl_context,
    server_side=False,
    server_hostname="example.com",
)

await aiofastnet.sendfile(transport, fileobj)

When aiofastnet Is a Good Fit

aiofastnet is most attractive when you already rely on asyncio's transport/protocol APIs and one or more of these are true:

• You have long-lived TCP or TLS connections.
• You run protocol-heavy services where transport overhead is visible in CPU profiles.
• You maintain a library and want better performance without changing your public API.
• You care about consistent write() / writelines() buffer behavior.
• You want SSL flow control to reflect the whole buffered stack, not only part of it.

When Not To Use aiofastnet

aiofastnet is not the right default for every networking project:

• If your workload is dominated by very short-lived connections, you should expect little or no gain. aiofastnet focuses on optimizing the data path after connection establishment.

Platform Compatibility

aiofastnet is built and tested on Linux, macOS, and Windows. It works with the standard asyncio event loop, uvloop, and winloop.

On Windows it works with SelectorEventLoop and winloop. With ProactorEventLoop it falls back to asyncio's native connection and server implementation, because the proactor loop does not provide the add_reader() / add_writer() hooks required by aiofastnet's custom transport implementation. For transports created through aiofastnet, a compatibility wrapper preserves the documented write() / writelines() buffer-safety behavior.

Building From Source

1. Clone the repository:

   $ git clone git@github.com:tarasko/aiofastnet.git
   $ cd aiofastnet
   

2. Create and activate a virtual environment:

   $ python3 -m venv aiofn-dev
   $ source aiofn-dev/bin/activate
   

3. Install test dependencies:

   $ pip install -r requirements-test.txt
   

4. Build extensions in place and run tests:

   $ python setup.py build_ext --inplace
   $ pytest -s -v
   

5. Run the benchmark:

   $ python -m examples.benchmark
   

Contributing

Contributions are welcome.