Lagging and artifacts displayed on screen when typing key frequently

[cool4zbl]

I found a strange bug recently when typing hjkl frequently to move the cursor in normal mode,
vim repeated occasional hjkl letters, see the below figure.

so when moving left with h, some of the cursor through the local characters into h.
But in my observation found that the content did not actually change that character, as if covered with a layer in the above.
I tried exit vim and re-open the file, but in normal mode the same problem occurred again when I move the cursor frequently. Stuck in a long time and did not know why.

So I decided to dig in and do the steps below:

1. Comment out (or remove) about half your vimrc file.
2. Restart Vim, or open a new Vim (reloading the vimrc is not good enough, as settings aren't unset).
3. Is the problem now gone? Put back the part you removed out (keeping Vim open and using undo is useful here) and repeat step 1 on the part you added back.
4. Does the problem still occur? Go to step 1.

Finally, I found if I comment vim-wakatime plugin, this problem solved!
Seemed it was processing a Python command when the bug occurred.

Environment: Mac OS 10.12.6,

 vim --version
VIM - Vi IMproved 8.0 (2016 Sep 12, compiled Jan 30 2017 04:49:52)
MacOS X (unix) version
Included patches: 1-271
Compiled by Homebrew
Huge version without GUI.  Features included (+) or not (-):
+acl             +file_in_path    +mouse_sgr       +tag_old_static
+arabic          +find_in_path    -mouse_sysmouse  -tag_any_white
+autocmd         +float           +mouse_urxvt     -tcl
-balloon_eval    +folding         +mouse_xterm     +termguicolors
-browse          -footer          +multi_byte      +terminfo
++builtin_terms  +fork()          +multi_lang      +termresponse
+byte_offset     -gettext         -mzscheme        +textobjects
+channel         -hangul_input    +netbeans_intg   +timers
+cindent         +iconv           +num64           +title
-clientserver    +insert_expand   +packages        -toolbar
+clipboard       +job             +path_extra      +user_commands
+cmdline_compl   +jumplist        +perl            +vertsplit
+cmdline_hist    +keymap          +persistent_undo +virtualedit
+cmdline_info    +lambda          +postscript      +visual
+comments        +langmap         +printer         +visualextra
+conceal         +libcall         +profile         +viminfo
+cryptv          +linebreak       +python          +vreplace
+cscope          +lispindent      -python3         +wildignore
+cursorbind      +listcmds        +quickfix        +wildmenu
+cursorshape     +localmap        +reltime         +windows
+dialog_con      -lua             +rightleft       +writebackup
+diff            +menu            +ruby            -X11
+digraphs        +mksession       +scrollbind      -xfontset
-dnd             +modify_fname    +signs           -xim
-ebcdic          +mouse           +smartindent     -xpm
+emacs_tags      -mouseshape      +startuptime     -xsmp
+eval            +mouse_dec       +statusline      -xterm_clipboard
+ex_extra        -mouse_gpm       -sun_workshop    -xterm_save
+extra_search    -mouse_jsbterm   +syntax
+farsi           +mouse_netterm   +tag_binary
   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/local/share/vim"
Compilation: clang -c -I. -Iproto -DHAVE_CONFIG_H   -DMACOS_X_UNIX  -g -O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
Linking: clang   -L. -fstack-protector -L/usr/local/lib -L/usr/local/opt/libyaml/lib -L/usr/local/opt/openssl/lib -L/usr/local/opt/readline/lib  -L/usr/local/lib -o vim        -lncurses -liconv -framework Cocoa   -mmacosx-version-min=10.12 -fstack-protector-strong -L/usr/local/lib  -L/usr/local/Cellar/perl/5.24.0_1/lib/perl5/5.24.0/darwin-thread-multi-2level/CORE -lperl -lm -lutil -lc -F/usr/local/opt/python/Frameworks -framework Python   -lruby.2.4.0 -lobjc

Hoping there is a solution.

[alanhamlett]

Try adding this line to your ~/.vimrc file:

let g:wakatime_ScreenRedraw = 1

Then restart Vim.

[cool4zbl]

@alanhamlett
I'm sorry, adding let g:wakatime_ScreenRedraw = 1 to my ~/.vimrc do not solve the issue.
It occurs again.
😕

[alanhamlett]

For now if this happens you can redraw the screen with this command:

:redraw!

The redraw setting should run that command automatically, so I'll find out why it's not working.

[evturn]

I have also been experiencing this when using the hjkl keys after vim has been idle for more than a few seconds. I also tried this using Neovim with the same .vimrc and plugins only it doesn't print the characters but instead freezes for the same duration in which the characters would be printed in vim.

[alanhamlett]

d7b6f18 sets the default redraw setting to enabled if the plugin takes too long forking the wakatime-cli process. After updating vim-wakatime, is this issue fixed?

[evturn]

@alanhamlett that did the trick. thanks for for the help!

[alanhamlett]

@cool4zbl does this fix it for you too?

[alanhamlett]

Fixed in v6.0.0 using Vim 8.0+ async.