Emacs freezes when open a python file with lsp backend

[eakirtas]

Description

I am using Emacs along with spacemacs to python development. Today I decide to
change my backend into lsp backend. I've checkout out to dev branch and I
followed the guide for LSP-layer.

Although setups seems right, every time I open a python file emacs freeze. To be
more accurate, the emacs seems running but moving cursor takes a whole minute.

I can't figure out what happening and I didn't found any related issue

Reproduction guide 🪲

• Start Emacs
• C-x C-f open a .py file

Observed behaviour: 👀 💔
UI seems to freeze

Spacemacs configuration about python-layer

     (python
      :variables
      python-backend 'lsp
      python-lsp-server 'mypyls
      python-formatter 'yapf
      python-lsp-git-root "~/.lib/python-language-server"
      python-enable-yapf-format-on-save t
      python-test-runner 'pytest
      python-save-before-test nil
      python-fill-column 99
      python-sort-imports-on-save t
      )

System Info 💻

• OS: gnu/linux
• Emacs: 26.3
• Spacemacs: 0.300.0
• Spacemacs branch: develop (rev. c3872f1)
• Graphic display: t
• Distribution: spacemacs
• Editing style: hybrid
• Completion: helm
• Layers:

(octave csv rust haskell
        (javascript :variables javascript-disable-tern-port-files nil)
        yaml php ipython-notebook html lsp helm
        (auto-completion :variables auto-completion-enable-help-tooltip t)
        emacs-lisp git org spell-checking syntax-checking version-control
        (c-c++ :variables c-c++-enable-clang-support t)
        semantic cscope gtags tmux shell-scripts python-notebook
        (python :variables python-backend 'lsp python-lsp-server 'mypyls python-formatter 'yapf python-lsp-git-root "~/.lib/python-language-server" python-enable-yapf-format-on-save t python-test-runner 'pytest python-save-before-test nil python-fill-column 99 python-sort-imports-on-save t))

• System configuration features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB NOTIFY LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS LIBSYSTEMD LCMS2

[eakirtas]

Here is the profiler-report when just moving the cursor around

 - call-interactively                                     204,150,774  85%
  - funcall-interactively                                 204,150,774  85%
   - spacemacs/helm-M-x-fuzzy-matching                    200,293,907  83%
    - let                                                 200,293,907  83%
     - call-interactively                                 200,289,779  83%
      - funcall-interactively                             200,289,763  83%
       - helm-M-x                                         200,289,763  83%
        - helm-M-x-read-extended-command                  200,288,707  83%
         - helm                                           199,645,163  83%
          - apply                                         199,644,139  83%
           - helm                                         199,644,139  83%
            - apply                                       199,644,139  83%
             - helm-internal                              199,644,139  83%
              + helm-read-pattern-maybe                    84,898,945  35%
              + helm-display-buffer                        66,263,734  27%
              + helm-execute-selection-action              48,322,413  20%
              + helm-initialize                               114,232   0%
              + #<compiled 0x17b8591>                          31,175   0%
              + select-window                                   8,448   0%
                advice-add                                      4,136   0%
            helm-parse-keys                                     1,024   0%
         + helm-make-source                                   639,408   0%
     + add-to-list                                              4,128   0%
   + previous-line                                          3,834,371   1%
   + mouse-drag-region                                          8,448   0%
   + mouse-set-point                                            7,392   0%
   + handle-focus-in                                            5,600   0%
   + lsp-ui-doc--handle-mouse-movement                          1,056   0%

[arifer612]

#14342 is a relevant active issue