caio

Python wrapper for AIO

NOTE: Native Linux aio implementation supports since 4.18 kernel version.

Python bindings for Linux AIO API and simple asyncio wrapper.

Example

import asyncio
from caio import AsyncioContext

loop = asyncio.get_event_loop()

async def main():
    # max_requests=128 by default
    ctx = AsyncioContext(max_requests=128)

    with open("test.file", "wb+") as fp:
        fd = fp.fileno()

        # Execute one write operation
        await ctx.write(b"Hello world", fd, offset=0)

        # Execute one read operation
        print(await ctx.read(32, fd, offset=0))

        # Execute one fdsync operation
        await ctx.fdsync(fd)

        op1 = ctx.write(b"Hello from ", fd, offset=0)
        op2 = ctx.write(b"async world", fd, offset=11)

        await asyncio.gather(op1, op2)

        print(await ctx.read(32, fd, offset=0))
        # Hello from async world


loop.run_until_complete(main())

Troubleshooting

The linux implementation works normal for modern linux kernel versions and file systems. So you may have problems specific for your environment. It's not a bug and might be resolved some ways:

• Upgrade the kernel
• Use compatible file system
• Use threads based or pure python implementation.

The caio since version 0.7.0 contains some ways to do this.

• In runtime use the environment variable CAIO_IMPL with possible values:
  • linux - use native linux kernels aio mechanism
  • thread - use thread based implementation written in C
  • python - use pure python implementation
• File default_implementation located near __init__.py in caio installation path. It's useful for distros package maintainers. This file might contains comments (lines starts with # symbol) and the first line should be one of linux thread or python.

Previous versions allows direct import of the target implementation.