Like many other developers, I’ve configured my prompt’s $PS1 to display my
current branch in Git:
st-brandur1 my-project(master*) $
This is accomplishing by invoking Oh-My-Zsh’s git_prompt_info function. Bash
has a similar mechanism called __git_ps1.
This worked great for me for years until I started working in repositories with
very large Git histories. You can see it for yourself by cloning down the Linux
kernel tree, Rust, or Servo, which all demonstrate the effect.
git_prompt_info takes so long to return that the latency becomes disruptive
when typing commands in quick succession.
git_prompt_info calls into git status. Along with getting the current
branch name, it returns another piece of information: whether the repository is
“dirty” in that it has uncommitted changes. In the prompt line above, that
manifests as the * shown after the branch name. This dirty check is very slow
and was single-handedly responsible for my unresponsive prompt.
Luckily, Oh-My-Zsh is good enough to include an option to skip the dirty check. It’s set as part of Git configuration:
$ git config --add oh-my-zsh.hide-dirty 1
Bash includes something very similar:
$ git config bash.showDirtyState false
My problems with a slow prompt evaporated instantly.
Did I make a mistake? Please consider sending a pull request.