enable_compression doesn't work with FileResponse in sendfile mode

[savv]

Long story short

response.enable_compression doesn't work on Heroku.

Expected behaviour

enable_compression on a response should work on Heroku.

Actual behaviour

While this worked locally just fine, Heroku didn't like it when I enabled compression on a FileResponse:
Apr 17 11:58:19 my-app-staging heroku/router: http_error="Bad chunk" at=error code=H17 desc="Poorly formatted HTTP response" method=GET path="/" host=my-app-staging.herokuapp.com request_id=0bc47133-af19-4999-bc0f-179054b7388a fwd="xx.xx.xx.xx" dyno=web.1 connect=0ms service=19ms status=503 bytes= protocol=https
Apr 17 11:58:19 my-app-staging heroku/router: http_error="Bad chunk" at=error code=H17 desc="Poorly formatted HTTP response" method=GET path="/" host=my-app-staging.herokuapp.com request_id=9c1b4583-61d5-4867-bf1a-75de194cf71f fwd="xx.xx.xx.xx" dyno=web.1 connect=0ms service=5ms status=503 bytes= protocol=https
Apr 17 11:58:23 my-app-staging heroku/router: http_error="Bad chunk" at=error code=H17 desc="Poorly formatted HTTP response" method=GET path="/" host=my-app-staging.herokuapp.com request_id=a2f80aee-0ba0-4117-9139-123a79fd2f1c fwd="xx.xx.xx.xx" dyno=web.1 connect=0ms service=3ms status=503 bytes= protocol=https

Steps to reproduce

        resp = web.FileResponse('./dist/index.html', headers={'Cache-Control': 'no-cache'})
        resp.enable_compression()
        return resp

Your environment

aiohttp==2.3.6
Using aiohttp directly on Heroku (no gunicorn/etc).

[asvetlov]

Try to set AIOHTTP_NOSENDFILE=1 environment variable.

[savv]

Works now, thanks. Is there a way to set this programmatically?

[asvetlov]

Not yet.
The problem is: aiohttp uses sendfile syscall even for compressed files.
The fast path should be disabled for non-identity content encoding.

The path for FileResponse is welcome (the required change is relatively simple).

[asvetlov]

The issue is waiting for a champion.

[roganov]

I'll take this one.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a [new issue] for related bugs.
If you feel like there's important points made in this discussion, please include those exceprts into that [new issue].
[new issue]: https://github.com/aio-libs/aiohttp/issues/new