[PATCH] git-status.txt: mention --no-optional-locks

[Jeff King <peff@peff.net>]

On Mon, Nov 27, 2017 at 12:24:43AM -0500, Jeff King wrote:

> > If people have to ask on the mailing list even after reading the man
> > pages, that's a strong indicator that we could do better.
> 
> Sure. That's why I suggested improving the documentation in my last
> email. But in all the discussion, I haven't seen any patch to that
> effect.

Maybe like this.

-- >8 --
Subject: [PATCH] git-status.txt: mention --no-optional-locks

If you come to the documentation thinking "I do not want Git
to take any locks for my background processes", then you may
easily run across "--no-optional-locks" in git.txt.

But it's quite reasonable to hit a specific instance of the
problem: you have "git status" running in the background,
and you notice that it causes lock contention with other
processes. So you look in git-status.txt to see if there is
a way to disable it, but there's no mention of the flag.

Let's add a short note mentioning that status does indeed
touch the index (and why), with a pointer to the global
option. That can point users in the right direction and help
them make a more informed decision about what they're
disabling.

Signed-off-by: Jeff King <peff@peff.net>
---
 Documentation/git-status.txt | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/git-status.txt b/Documentation/git-status.txt
index fc282e0a92..81cab9aefb 100644
--- a/Documentation/git-status.txt
+++ b/Documentation/git-status.txt
@@ -387,6 +387,19 @@ ignored submodules you can either use the --ignore-submodules=dirty command
 line option or the 'git submodule summary' command, which shows a similar
 output but does not honor these settings.
 
+BACKGROUND REFRESH
+------------------
+
+By default, `git status` will automatically refresh the index, updating
+the cached stat information from the working tree and writing out the
+result. Writing out the updated index is an optimization that isn't
+strictly necessary (`status` computes the values for itself, but writing
+them out is just to save subsequent programs from repeating our
+computation). When `status` is run in the background, the lock held
+during the write may conflict with other simultaneous processes, causing
+them to fail. Scripts running `status` in the background should consider
+using `git --no-optional-locks status` (see linkgit:git[1] for details).
+
 SEE ALSO
 --------
 linkgit:gitignore[5]
-- 
2.15.0.687.g5a800c9f78