Watching folder makes it impossible to delete/rename parent folder on Windows

[Cruor]

Manually watching folders recursively for changes prevents anything but bottom level watched folders from being renamed/deleted. Using both the example and minimum reproducible code below the user is unable to rename watched_folder and foo, but can rename bar freely. If another folder baz is created in bar without being watched then bar will not be prevented from being deleted/renamed. Using a different timeout over the threshold of 0.01 does not change this behavior. Seems like Windows believes the watching is a open handle that prevents modification.

Are there any other options for recursively watching for file changes that does not cause these issues?

Example manual recursion use case

using FileWatching

mkpath("watched_folder/foo/bar/baz")
watch_folder("watched_folder", 0.0)
watch_folder("watched_folder/foo", 0.0)
watch_folder("watched_folder/foo/bar", 0.0)
# Omitting baz on purpose

println("Enter to exit")
readline()

Minimum reproducible code

using FileWatching

mkpath("watched_folder/foo/bar/baz")
watch_folder("watched_folder/foo/bar", 0.0)

println("Enter to exit")
readline()

Version info

Julia Version 1.4.1
Commit 381693d3df* (2020-04-14 17:20 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-8.0.1 (ORCJIT, sandybridge)
Environment:
  JULIA_NUM_THREADS = 4

[StefanKarpinski]

Yep, that's how Windows works, unfortunately. I don't think there's anything we can do about it. If something is open by any application on Windows, it cannot be deleted or renamed. It's a massive pain in the butt.

[Cruor]

Watchdog package from Python does not have this problem though. Using their example code from https://pypi.org/project/watchdog/ works just as expected, and automatically does the recursion for you. From what I can gather that uses the event based Observer by default, as a later example explicitly uses PollingObserver. Maybe this is just a limitation with the current FileWatching implementation?

>python watch.py
2020-07-31 17:01:37 - Created file: .\watched_folder\New Text Document.txt
2020-07-31 17:01:37 - Modified directory: .\watched_folder
2020-07-31 17:01:39 - Modified directory: .\watched_folder\foo\bar\baz
2020-07-31 17:01:40 - Deleted file: .\watched_folder\New Text Document.txt
2020-07-31 17:01:40 - Modified directory: .\watched_folder
2020-07-31 17:01:44 - Moved directory: from .\watched_folder\foo\bar to .\watched_folder\bar\bar
2020-07-31 17:01:44 - Moved directory: from .\watched_folder\foo\bar\baz to .\watched_folder\bar\bar\baz
2020-07-31 17:01:44 - Moved directory: from .\watched_folder\foo to .\watched_folder\bar
2020-07-31 17:01:44 - Modified directory: .\watched_folder
2020-07-31 17:01:44 - Modified directory: .\watched_folder\bar
2020-07-31 17:01:48 - Moved directory: from .\watched_folder\bar\bar to .\watched_folder\foo\bar
2020-07-31 17:01:48 - Moved directory: from .\watched_folder\bar\bar\baz to .\watched_folder\foo\bar\baz
2020-07-31 17:01:48 - Moved directory: from .\watched_folder\bar to .\watched_folder\foo
2020-07-31 17:01:48 - Modified directory: .\watched_folder
2020-07-31 17:01:48 - Modified directory: .\watched_folder\foo

[StefanKarpinski]

Maybe this is just a limitation with the current FileWatching implementation?

Entirely possible. If someone wants to figure out how watchdog is doing this that would be great.