Sometimes artifact uploads silently fail, resulting in 0B files

[alahiff]

A major problem (e.g. completely invalid presigned URL) results in the client failing, but there have been recent examples where artifact (object) uploads result in 0B objects even though the artifact size is over 300 MB. It's possibly related to time-outs or similar issues. The problem may occur in environments when there is high latency and low bandwidth.

[james-panayis]

Note that I can reproduce this when trying to upload a relatively large (eg 500MB) file from my relatively slow home internet connection.

[alahiff]

@james-panayis In the upload method in the file simvue/api/objects/artifact/base.py, after this:

        _response = sv_post(
            url=_url,
            headers={},
            params={},
            is_json=False,
            files={"file": file},
            data=self._init_data.get("fields"),
        )

could you please print the status code and returned text? E.g.

print("Upload response:", _response.status_code, _response.text)

And please let me know what you get if the error occurs?

[james-panayis]

@alahiff It prints:

Upload response: 204

[alahiff]

That indicates success of course. Does that definitely give a 0B file?

[james-panayis]

Yep - see run test_large_artifact_file_upload. The UI suggests it has worked properly, but if you try to download the file it's 0B.

[alahiff]

I tried increasing DEFAULT_API_TIMEOUT in simvue/api/request.py and it solved the problem for me.

As well as increasing the timeout for file uploads, we need to ensure that a timeout doesn't result in the Python API saying the file was uploaded successfully. The status code is 204, even in the event of a timeout, which is interesting...