Input delay when using ray-x/lsp_signature.nvim

[mgnsk]

FAQ

• I have checked the FAQ and it didn't resolve my problem.

Announcement

• I have checked Breaking change announcement.

Minimal reproducible full config

local lazypath = vim.fn.stdpath("data") .. "/lazy/lazy.nvim"
if not vim.loop.fs_stat(lazypath) then
    vim.fn.system({
        "git",
        "clone",
        "--filter=blob:none",
        "https://github.com/folke/lazy.nvim.git",
        "--branch=stable", -- latest stable release
        lazypath,
    })
end
vim.opt.rtp:prepend(lazypath)

require("lazy").setup({
    {
        "ray-x/lsp_signature.nvim",
    },
    {
        "neovim/nvim-lspconfig",
        config = function()
            local lsp = require("lspconfig")
            local capabilities = vim.lsp.protocol.make_client_capabilities()

            local function on_attach(client, bufnr)
                require("lsp_signature").on_attach({}, bufnr)
            end

            lsp.gopls.setup({ capabilities = capabilities, on_attach = on_attach })

            vim.lsp.handlers["textDocument/publishDiagnostics"] =
                vim.lsp.with(vim.lsp.diagnostic.on_publish_diagnostics, {
                    update_in_insert = false,
                })
        end,
    },
    {
        "hrsh7th/nvim-cmp",
        commit = "09ff53f",
        dependencies = {
            "hrsh7th/cmp-nvim-lsp",
        },
        config = function()
            local cmp = require("cmp")
            cmp.setup({
                snippet = {
                    expand = function(args) end,
                },
                sources = {
                    { name = "nvim_lsp" },
                },
                mapping = {
                    ["<Tab>"] = cmp.mapping(cmp.mapping.select_next_item(), { "i", "s" }),
                    ["<CR>"] = cmp.mapping(cmp.mapping.confirm({
                        behavior = cmp.ConfirmBehavior.Insert,
                        select = true,
                    })),
                },
            })
        end,
    },
})

Description

The input delay was supposedly fixed (#1606, #1608) but the issue is still there. Also linking a related issue: ray-x/lsp_signature.nvim#273.

Steps to reproduce

Repro (requires docker):

git clone https://github.com/mgnsk/nvim-cmp-stutter-repro.git
cd nvim-cmp-stutter-repro
bash build.sh
bash run.sh

Now move inside a go function, type append(, wait for the signature and completion to pop up and try to type the letter c 4 times as fast as possible. It seems to occur in about 4 out of 5 attempts.

Expected behavior

Expected no stutter.

Actual behavior

Recording of the stutter with ray signature in use: https://asciinema.org/a/EMs6LU8QXUYntcm9Gkf3oy58l

Without ray signature, no stutter: https://asciinema.org/a/KMSlHcFPWyPKw1yJNhinwCH56

Additional context

As a hack, the stutter goes away when this function:

nvim-cmp/lua/cmp/init.lua

Lines 86 to 89 in 09ff53f

	---Return view is visible or not.
	cmp.visible = cmp.sync(function()
	return cmp.core.view:visible() or vim.fn.pumvisible() == 1
	end)

is changed to

---Return view is visible or not.
cmp.visible = function()
  return cmp.core.view:visible() or vim.fn.pumvisible() == 1
end

indicating that the delay comes from cmp.sync().

[mgnsk]

It seems to be introduced in #1583. The commit before that didn't stutter.

The cmp.visible() function was made synchronous in 0d23640

It seems like these functions should be synchronous with regards to the global filter and not with regards to the UI.

Also in ray signature, I tried completely removing the call to cmp.visible() and it still worked, without the stutter now. So maybe something can be done there.