SMB: errors ignored when connecting

[frafra]

The system tries to connect 5 times in a row, ignoring all errors. Since the for loop has no else branch, the function does not raise any error when all tentative failed.

filesystem_spec/fsspec/implementations/smb.py

Lines 123 to 136 in 05e7d80

	for _ in range(5):
	try:
	smbclient.register_session(
	self.host,
	username=self.username,
	password=self.password,
	port=self._port,
	encrypt=self.encrypt,
	connection_timeout=self.timeout,
	)
	break
	except Exception:
	time.sleep(0.1)

[martindurant]

You are quite right! Would you like to implement a fix?

[frafra]

I would suggest dropping the multiple tentative: if the connection is unstable, it should be up to the user to rely on some automatic retry mechanism such as tenacity or backoff. What is your opinion on that?

[martindurant]

I don't know what the user's workflow might be or how they would apply those tools, but in our own CI pipelines, SMB is unstable for some reason, and this loop makes tests fail less often.

[frafra]

Since it is a problem with how the CI is configured, I would suggest applying such workaround to the CI only,

[martindurant]

Plenty of other implementations have retry loops for connection errors, why do you think it's a problem here?

[frafra]

Well, I am not familiar with SMB, but generally a failing connection hints at some underlying issues. If SMB is intrinsically unstable, it would be nice to have a reference to in the code (why wait 0.1 seconds? why trying just 5 times?).
Automatic retry can be a feature whenever it is needed, but the developer should be in control of that; otherwise one could end up with a connection which usually takes 5 tentative, and sometimes 6, so it would apparently fail randomly without even having a warning logged by the library.

Is SMB supposed to randomly fail? Is it a documented behavior? Or is it a common misconfiguration or glitch that the developer/user should be made aware of?