TaskVineExecutor: write function data to temp directory

[colinthomas-z80]

Description

This moves the working directory for TaskVine executor function data to a directory in /tmp

These files were previously written adjacent to the logging in the working directory. They may be written in excess when running a large number of tasks.

Type of change

Choose which options apply, and delete the ones which do not apply.

• New feature

[benclifford]

I ran in my dev container and I got this surprise.

>       tmp_dir = os.path.join('/tmp/', f'{self.label}-{os.getlogin()}')
E       OSError: [Errno 6] No such device or address

[benclifford]

did some strace, and it's looking in this file which contains a decimalised unsigned 32 bit integer representation of signed 32-bit -1:

$ cat /proc/self/loginuid 
4294967295

and then failing after that.

The documentation for Python's os.getlogin says

https://docs.python.org/3/library/os.html#os.getlogin

For most purposes, it is more useful to use getpass.getuser()

and in my dev environment that is able to figure out who I am:

>>> import getpass
>>> getpass.getuser()
'benc'

[benclifford]

This is more a reference for readers of #1122 that review comment for @colinthomas-z80 - here's another instance of using a timestamp as a unique ID that #1122 might want to address

[benclifford]

Github Actions testing shows that same OS error - it's not just my wacky dev environment.

[colinthomas-z80]

I do recognize the potential issues using datetime. In this instance it is specific to milliseconds so a conflict is unlikely. My rationale was to follow a logging convention in taskvine that will show the logs in a directory listing by order of creation, so it is easier to locate the most recent run. Though these files are rarely useful for a user to inspect themselves. I can change to uuid if you think it conforms better.

[benclifford]

I do recognize the potential issues using datetime.

I don't think there's anything to be too concerned about here... mostly I was tagging it for the eventual implementer of #1122 to come fix it up.

[khk-globus]

I do recognize the potential issues using datetime.

I don't think there's anything to be too concerned about here... mostly I was tagging it for the eventual implementer of #1122 to come fix it up.

FWIW, this is precisely the purview of the tempfile module [docs.python.org]. Consider:

import tempfile
...
def ...:
    ...
    now_str = datetime.now().strftime(...)
    prefix = f"{self.label}-{getpass.getuser()}-{now_str}-"
    tmp_dir = tempfile.TemporaryDirectory(prefix=prefix, delete=False)

At which point tmp_dir will have the property of sortability you've stated was your goal and will also be guaranteed unique (that's tempfile's guarantee).

I'm not saying it's the best solution in this precise scenario, but I do observe that temporary files are not as immediately trivial as many assume at first glance — there's a reasion mktemp (command) and Python's tempfile module exist.

[colinthomas-z80]

I like that option. I was also hoping to delete the directory at the end and it takes care of that. Thanks!

[benclifford]

I just merged this into my kubernetes test PR #3482 after getting distracted making task vine work in there, to give me some more assurance about how this works when workers do not have a shared filesystem with the submit side. It works ok.