Occasional failure in HTTP bytes about dask-examples HOT 7 OPEN

HTTPFileSystem might now return a HTTPStreamFile where previously it returned a raw file-like requests response object. I don't think this changes anything from dask's point of view, except that we don't even try the "lets see if this is smaller than a block" approach. A retry would have to be for the whole of the request, not each call to read. However, a retry on establishing the connection (here) would make sense.

from dask-examples.

I'm not sure there's much we can do about broken connections, I can't see that it could be any fault of ours; retries could be built into the HTTPFileSystem, but perhaps it's better to retry the whole tasks in such cases.

from dask-examples.

Is there a good reason to avoid retries in HTTPFileSystem?

from dask-examples.

No, but a couple of things that make it tricky:

• it is tricky to consider which set of errors should lead to a retry. Perhaps would have to retry everything
• some things, like establishing the initial connection, are already retried by requests/urllib
• if it's a timeout, then a set of retries might take a very long time to fail
• in the fsspec implementation, there is a non-seekable fallback mode when the file-size is unavailable, that gives you a requests file-like object rather than a HTTPFile. I don't think we can easily intercept its read methods for the purposes of catching errors.

from dask-examples.

This SO answer might be the best way to do it globally: https://stackoverflow.com/a/15431343/3821154 , allows you to be explicit about retries following a connection error that should apply to all connections within a session

from dask-examples.

Quite some refactoring of fsspec's HTTP implementation lately.

Are dask tests still flaky?
AFAICS, fsspec now returns an HTTPFile even if range requests are not possible. Does that mean a retry policy in fsspec makes more sense now @martindurant?

from dask-examples.

(feel free to implement that in a PR, in case you have the time)

from dask-examples.