Improve diagnostic for Git fsmonitor settings in Homebrew repository:

[mfilippov]

• Added a check for the core.fsmonitor setting in the Homebrew repository
• Provided an error message with instructions to disable fsmonitor if it is set to 'true'
• Ensured the instructions specify making the change in the Homebrew repository folder

This update helps prevent potential issues with lock files during 'brew upgrade' operations.

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

[carlocab]

We already set core.fsmonitor to false during brew update.

Is this not working for you?

[mfilippov]

@carlocab It didn't work for me. I received message from brew about another process running. I checked running process and find git fsmonitor process which hold lock file.

[carlocab]

What's the output of your brew config?

[mfilippov]

HOMEBREW_VERSION: 4.3.10
ORIGIN: https://github.com/Homebrew/brew
HEAD: c3ae0327c01aab461531bfc0fcdfb4dd3a779205
Last commit: Good "git" signature with ECDSA key SHA256:ZtBmHHUCxZtGFkIZAmRhzIN1Pj37nqiL5sRRyoFxc2c
No principal matched.
16 hours ago
Core tap JSON: 19 Jul 08:59 UTC
Core cask tap JSON: 19 Jul 08:59 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_BAT_THEME: GitHub
HOMEBREW_CASK_OPTS: []
HOMEBREW_EDITOR: /opt/homebrew/bin/micro
HOMEBREW_MAKE_JOBS: 10
HOMEBREW_NO_ANALYTICS: set
Homebrew Ruby: 3.3.3 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.3.3/bin/ruby
CPU: 10-core 64-bit arm_firestorm_icestorm
Clang: 15.0.0 build 1500
Git: 2.45.2 => /opt/homebrew/bin/git
Curl: 8.6.0 => /usr/bin/curl
macOS: 14.5-arm64
CLT: 15.3.0.0.1.1708646388
Xcode: 15.4
Rosetta 2: false

[Bo98]

I don't see how the instructions here do anything different to:

brew/Library/Homebrew/cmd/update.sh

Lines 578 to 582 in eda3039

	if [[ "${DIR}" = "${HOMEBREW_REPOSITORY}" && "${HOMEBREW_REPOSITORY}" = "${HOMEBREW_PREFIX}" ]]
	then
	# Git's fsmonitor prevents the release of our locks
	git config --bool core.fsmonitor false
	fi

Might be worth debugging why that's not kicking in on your system.

The Last commit line in your brew config seems to have extra output too.

[MikeMcQuaid]

Thanks for the PR! Unfortunately, also want to hold off on this until we figure out what's not working with the existing logic.

[mfilippov]

You right I see set fsmonitor false now. Maybe I have old version of brew or something strange happened. I will investigate issue if it will happen again.

[mfilippov]

@carlocab I think I found the reason for the issue:

COMMAND   PID      USER   FD     TYPE             DEVICE SIZE/OFF                NODE NAME
git     39004 mfilippov  cwd      DIR               1,16     2016              255440 /Users/mfilippov
git     39004 mfilippov  txt      REG               1,16  3599840           560946711 /opt/homebrew/Cellar/git/2.45.2/bin/git
git     39004 mfilippov  txt      REG               1,16   162656           468225747 /opt/homebrew/Cellar/gettext/0.22.5/lib/libintl.8.dylib
git     39004 mfilippov  txt      REG               1,16   545424           560918824 /opt/homebrew/Cellar/pcre2/10.44/lib/libpcre2-8.0.dylib
git     39004 mfilippov    0u     CHR                3,2      0t0                 333 /dev/null
git     39004 mfilippov    1u     CHR                3,2      0t0                 333 /dev/null
git     39004 mfilippov    2u     CHR                3,2      0t0                 333 /dev/null
git     39004 mfilippov    3u  KQUEUE                                                 count=0, state=0x8
git     39004 mfilippov    4r     DIR               1,16      288           154470969 /opt/homebrew/Library/Taps/umputun/homebrew-apps
git     39004 mfilippov    5r     DIR               1,16       96           154470968 /opt/homebrew/Library/Taps/umputun
git     39004 mfilippov    6r     DIR               1,16      128              509384 /opt/homebrew/Library/Taps
git     39004 mfilippov    7r     DIR               1,16      192              506076 /opt/homebrew/Library
git     39004 mfilippov    8r     DIR               1,16     1088              390632 /opt/homebrew
git     39004 mfilippov    9r     DIR               1,16      128               26283 /opt
git     39004 mfilippov   10r     DIR               1,16      672 1152921500311879682 /System/Volumes/Data
git     39004 mfilippov   11r     DIR               1,16      448 1152921500312503192 /System/Volumes
git     39004 mfilippov   12r     DIR               1,16      320 1152921500311879701 /System
git     39004 mfilippov   13u    unix 0x2451ea5996091de5      0t0                     ->0xb8583a1fbf2fa97f
git     39004 mfilippov   14u    unix 0xb8583a1fbf2fa97f      0t0                     ->0x2451ea5996091de5
git     39004 mfilippov   16u    unix 0xedfafe2d23c7ab72      0t0                     /opt/homebrew/Library/Taps/umputun/homebrew-apps/.git/fsmonitor--daemon.ipc
git     39004 mfilippov  200w     REG               1,16        0           561638823 /opt/homebrew/var/homebrew/locks/update

/opt/homebrew/Library/Taps/umputun/homebrew-apps# git config --get core.fsmonitor      
true

Could you apply the same thing to repositories in Taps?

[carlocab]

We could, though I've been under the impression that that wouldn't be needed.

I wonder if we should just make sure that lock gets release (e.g. by closing file descriptor 200 at the end of update.sh, perhaps? Or just deleting it?).