High memory usage in Nvim with mason, mason-lspconfig, nvim-lspconfig

[sh-cau]

Describe the bug When I open any buffer that is a Matlab file, the LSP server starts and has ~2GB of memory on each tmux window. Since I use many windows for different repos simultaneously in one tmux session, my RAM tends to overflow if I am not careful. Also the language server process does not end when I just close the terminal containing the tmux session. If I close the windows individually, the corresponding processes also stop.

To Reproduce Steps to reproduce the behavior:

1. Start tmux
2. Open nvim and edit a matlab file
3. Open a new window Ctrl-b + c, go to that window, repeat 1.+2.
4. Open btop or top and filter for matlab process.

Expected behavior I would expect the LSP to be more lightweight and not use up so much RAM?! According to the screenshot, an entire MATLAB instance is started to run the language server?!

Screenshots

Useful Information

• OS Version: Ubuntu 20.04 with nvim v0.10.1
• Language Server Client: matlab_ls in combination with mason, mason-lspconfig and nvim-lspconfig
• Client Version: commit hash eb1aab2e85dcf461e070b3d34e85aff15fcb9ada
• Node version: v18.0.0
• (relevant) Lazy Nvim LSP config:

  
  return {
  {
      'williamboman/mason.nvim',
      config = function()
          require('mason').setup({})
      end
  },
  {
      'williamboman/mason-lspconfig.nvim', -- bridges Mason with nvim-lspconfig
      config = function()
          require('mason-lspconfig').setup({
              ensure_installed = {
                  'matlab_ls',
                  'bashls',
                  'lua_ls',
                  'clangd',
                  'ltex',
                  'marksman',
                  'gitlab_ci_ls',
                  'yamlls',
              },
          })
      end
  },
  {
      'neovim/nvim-lspconfig',
      dependencies = { 'hrsh7th/cmp-nvim-lsp'},
      config = function()
          local lspconfig = require('lspconfig')
          local capabilities = require('cmp_nvim_lsp').default_capabilities()
          lspconfig.matlab_ls.setup({
              capabilities = capabilities,
              filetypes = { "matlab" },
              settings = {
                  matlab = {
                      installPath = "/home/sh/programs/MATLAB/R2023a/", -- also tried not setting this
                      telemetry = false, 
                  },
              },
              single_file_support = true, -- also tried false 
          })
          lspconfig.bashls.setup({
              capabilities = capabilities,
              filetypes = { "sh", "zsh", "bash" },
              settings = {
                  bashls = {
                      lint = {
                          enable = true,
                          diagnostics = true,
                          use = { "shellcheck" },
                      },
                  },
              },
          })
          lspconfig.lua_ls.setup({
              capabilities = capabilities,
              settings = {
                  Lua = {
                      diagnostics = {
                          globals = { 'vim' } -- avoids warnings that vim is not found
                      }
                  }
              }
          })
          local function quickfix() vim.lsp.buf.code_action({ apply = true }) end
          local map = require('utils').map
          vim.api.nvim_create_autocmd('LspAttach', {
              callback = function(args)
                  -- mappings
              end
          })
      end
  },
  }

**Additional context**
--

[dklilley]

My suspicion is that, as with VS Code, Nvim does not share an instance of the language server between separate Nvim windows. Because of this, each window is instantiating a new instance of the language server, which is then starting its own MATLAB process.

We are aware of this higher-than-expected memory cost for running the language server, and are investigating options for reducing this in the future.

As we continue to look into this, it would be helpful to understand more about your workflow so we can ensure it is captured in our future solution. Can you give some more context about why you are using multiple Nvim windows instead of just one? Is this a Nvim limitation (only one repository per window), or is it more efficient for you?

[sh-cau]

I suspected as much. Yes, indeed, I am working with multiple (MATLAB) repos and each repo has its own tmux window but mainly for organization purposes, i.e., to keep the buffer list local to that particular repo, e.g., when I use :bufdo %s/old/new/g I don't mess up other repos.