Delay when formatting files on save

[rushilmehra]

Hi all, I'm in the process of moving my configuration for neovim to lua. I'm setting up null-ls for formatting via eslint_d and prettier (as these are needed for my fulltime job) and i'm noticing a delay when I save a file. Before this I used to use coc-eslint and coc-prettier, and never noticed any delay when saving a file. The lag is bad in typescript files, but even worse in jsx/tsx. Even for one line changes, it can take up to a second to actually format.

This is my first time setting stuff up in lua, so maybe i'm doing something wrong? Here is my null-ls.lua:

local null_lus_status_ok, null_ls = pcall(require, 'null-ls')
if not null_lus_status_ok then
  return
end
local formatting = null_ls.builtins.formatting
local diagnostics = null_ls.builtins.diagnostics
null_ls.setup({
  debug = false,
  sources = {
    formatting.black.with({ extra_args = {'--fast'} }),
    formatting.prettier,
    formatting.eslint_d
  },
  on_attach = function(client)
    if client.resolved_capabilities.document_formatting then
      vim.cmd("autocmd BufWritePre <buffer> lua vim.lsp.buf.formatting()")
    end
  end,
})

[ghost]

Same is happening with me - any updates would be hugely appreciated.

[vuki656]

You have format on save which is causing the lag.

For me eslint_d takes a second or two most of the time to chew up the buffer. Plus I'm pretty sure you are running both eslint_d and prettier on save since they both format/lint js/ts/jsx/tsx.

I don't think you can make it instant and have format/lint on save.

The best bet would be to remove the auto command and call the formatting manually with a keymap.

[jose-elias-alvarez]

@rushilmehra If you mean what I use in my dotfiles, it's just a simple wrapper around formatting_sync() that automates server choice, so I don't think it's related.

[rushilmehra]

@jose-elias-alvarez I meant @vuki656 isn't using formatting_sync()

[vuki656]

@jose-elias-alvarez I meant @vuki656 isn't using formatting_sync()

I don't think that would affect it since I'm running only one formatted at a time. As far as I understand formatting_sync just makes sure multiple formatters are ran one after another. Didn't check tho.

[rushilmehra]

Ah yeah you're right, it shouldn't matter. I'll keep digging and see if I can find something. But yeah it might just be due to the large config file

[vuki656]

@jose-elias-alvarez I meant @vuki656 isn't using formatting_sync()

I don't think that would affect it since I'm running only one formatted at a time. As far as I understand formatting_sync just makes sure multiple formatters are ran one after another. Didn't check tho.

formatting_sync blocks the buffer which helps if formatting takes a long time and I'm not sure if it ran or silently failed so that's useful since I had occasions where I ran format, then cut some text and then formatting finished and messed up the whole file.