Try coc.vim for completion

after/plugin/general.vim

@@ -4,15 +4,17 @@ if !exists('g:deoplete#omni#input_patterns')
 endif
 
 " <C-h>, <BS>: close popup and delete backword char.
-inoremap <expr><C-h> deoplete#smart_close_popup()."\<C-h>"
-inoremap <expr><BS>  deoplete#smart_close_popup()."\<C-h>"
+"inoremap <expr><C-h> deoplete#smart_close_popup()."\<C-h>"
+"inoremap <expr><BS>  deoplete#smart_close_popup()."\<C-h>"
 
 inoremap <silent><expr> <TAB> 
       \ pumvisible() ? "\<C-n>" :
       \ <SID>check_back_space() ? "\<TAB>" :
-      \ "\<C-x><C-o>"
+      \ coc#refresh()
+      "\ '\<C-x><C-o>'
 
 function! s:check_back_space()
   let col = col('.') - 1
   return !col || getline('.')[col - 1]  =~ '\s'
 endfunction
+inoremap <silent><expr> <c-space> coc#refresh()

init.vim

@@ -44,7 +44,7 @@ set showcmd
 
 set ignorecase smartcase
 set inccommand=split
-set completeopt=menu,longest,preview
+set completeopt=menu,noinsert,preview
 set wildmode=list:longest,list:full
 set wildignore+=*.so,*.swp,*.zip,*.o
 set suffixes=.bak,~,.h,.info,.swp,.obj,.info,.aux,.dvi,.bbl,.out,.o,.lo,\.class

packages.vim

@@ -30,7 +30,9 @@ Plug 'Chiel92/vim-autoformat'
 
 " completion and snippets
 Plug 'SirVer/ultisnips' | Plug 'honza/vim-snippets'
-Plug 'Shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
+"Plug 'Shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
+Plug 'neoclide/coc.nvim', {'branch': 'release'}
+
 
 
 Plug '/usr/share/vim/vimfiles'