Ycm GotoDeclaration/Definition causes vim to freeze in certain cases

[ApolloBian]

Issue Prelude

Please complete these steps and check these boxes (by putting an x inside
the brackets) before filing your issue:

• I have read and understood YCM's [CONTRIBUTING][cont] document.
• I have read and understood YCM's [CODE_OF_CONDUCT][code] document.
• I have read and understood YCM's [README][readme], especially the
  [Frequently Asked Questions][faq] section.
• I have searched YCM's issue tracker to find issues similar to the one I'm
  about to report and couldn't find an answer to my problem. ([Example Google
  search.][search])
• If filing a bug report, I have included the output of vim --version.
• If filing a bug report, I have included the output of :YcmDebugInfo.
• If filing a bug report, I have attached the contents of the logfiles using
  the :YcmToggleLogs command.
• If filing a bug report, I have included which OS (including specific OS
  version) I am using.
• If filing a bug report, I have included a minimal test case that reproduces
  my issue, including what I expected to happen and what actually happened.
• I understand this is an open-source project staffed by volunteers and
  that any help I receive is a selfless, heartfelt gift of their free time. I
  know I am not entitled to anything and will be polite and courteous.
• I understand my issue may be closed if it becomes obvious I didn't
  actually perform all of these steps.

Thank you for adhering to this process! It ensures your issue is resolved
quickly and that neither your nor our time is needlessly wasted.

Issue Details

Provide a clear description of the problem, including the following key
questions:
I have used Ycm for over 2 years and everything works smoothly, however I recently encounter an issue where GotoDeclaration causes vim to freeze (not taking any kind of input including ^C etc) and after some time it says HTTPConnectionPool(host=.....): Read timed out. (read timeout=30). It is very annoying.

All the completion works fine tho, both identifier and semantic.

Include steps to reproduce here.
Include description of a minimal test case, including any actual code required
to reproduce the issue.
A minimal test case:

#!/usr/bin/env python
class TestCase:
  def __init__(self):
    self.somevalue = 0
  def reset_somevalue(self):
    self.somevalue = 0
  def inc_somevalue(self):
    self.somevalue += 1   # invoke on this line breaks vim
  def here_it_works_normal(self):
    self.reset_somevalues() # invoke on this line will jump to the definition

when invoking GoToDeclaration or GoToDefinition on the somevalue property, vim freezes.

• What did you expect to happen?
  jump to the __init__ function, or at least not freeze.

Diagnostic data

Output of vim --version

VIM - Vi IMproved 8.1 (2018 May 18, compiled Jan 28 2019 17:44:00)
macOS version
Included patches: 1-611
Compiled by bian_tianling@sjtu.edu.cn
Huge version without GUI.  Features included (+) or not (-):
+acl               +extra_search      +mouse_netterm     +tag_old_static
+arabic            +farsi             +mouse_sgr         -tag_any_white
+autocmd           +file_in_path      -mouse_sysmouse    -tcl
+autochdir         +find_in_path      +mouse_urxvt       +termguicolors
-autoservername    +float             +mouse_xterm       +terminal
-balloon_eval      +folding           +multi_byte        +terminfo
+balloon_eval_term -footer            +multi_lang        +termresponse
-browse            +fork()            -mzscheme          +textobjects
++builtin_terms    -gettext           +netbeans_intg     +textprop
+byte_offset       -hangul_input      +num64             +timers
+channel           +iconv             +packages          +title
+cindent           +insert_expand     +path_extra        -toolbar
-clientserver      +job               +perl              +user_commands
+clipboard         +jumplist          +persistent_undo   +vartabs
+cmdline_compl     +keymap            +postscript        +vertsplit
+cmdline_hist      +lambda            +printer           +virtualedit
+cmdline_info      +langmap           +profile           +visual
+comments          +libcall           -python            +visualextra
+conceal           +linebreak         +python3           +viminfo
+cryptv            +lispindent        +quickfix          +vreplace
+cscope            +listcmds          +reltime           +wildignore
+cursorbind        +localmap          +rightleft         +wildmenu
+cursorshape       -lua               +ruby              +windows
+dialog_con        +menu              +scrollbind        +writebackup
+diff              +mksession         +signs             -X11
+digraphs          +modify_fname      +smartindent       -xfontset
-dnd               +mouse             +startuptime       -xim
-ebcdic            -mouseshape        +statusline        -xpm
+emacs_tags        +mouse_dec         -sun_workshop      -xsmp
+eval              -mouse_gpm         +syntax            -xterm_clipboard
+ex_extra          -mouse_jsbterm     +tag_binary        -xterm_save
   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: "/Users/tianling/Applications/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H   -DMACOS_X -DMACOS_X_DARWIN  -g -O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
Linking: gcc   -L.  -L/usr/local/lib -o vim        -lncurses  -liconv -framework AppKit   -mmacosx-version-min=10.14 -fstack-protector-strong -L/usr/local/lib  -L/usr/local/Cellar/perl/5.28.1/lib/perl5/5.28.1/darwin-thread-multi-2level/CORE -lperl -lm -lutil -lc  -L/Users/tianling/.pyenv/versions/3.7.1/Python.framework/Versions/3.7/lib/python3.7/config-3.7m-darwin -lpython3.7m -framework CoreFoundation  -lruby.2.3.0 -lobjc

Output of YcmDebugInfo

Printing YouCompleteMe debug information...
-- Client logfile: /var/folders/5c/9r7xkl9x6zbc9hvykt4hnpsw0000gn/T/ycm_6vml8khq.log
-- Server Python interpreter: /Users/tianling/.pyenv/versions/3.7.1/Python.framework/Versions/3.7/bin/python
-- Server Python version: 3.7.1
-- Server has Clang support compiled in: True
-- Clang version: clang version 8.0.0 (tags/RELEASE_800/final)
-- No extra configuration file found
-- Python completer debug information:
--   Python interpreter: /Users/tianling/.pyenv/versions/3.7.1/envs/everything/bin/python
--   Python path: ['/Users/tianling/.pyenv/versions/3.7.1/Python.framework/Versions/3.7/lib/python37.zip', '/Users/tianling/.pyenv/versions/3.7.1/Python.framework/Versions/3.7/lib/python3.7', '/Users/tianling/.pyenv/versi
ons/3.7.1/lib/python3.7/lib-dynload', '/Users/tianling/.pyenv/versions/3.7.1/envs/everything/lib/python3.7/site-packages']
--   Python version: 3.7.1
--   Jedi version: 0.13.3
--   Parso version: 0.3.4
-- Server running at: http://127.0.0.1:50678
-- Server process ID: 7893
-- Server logfiles:
--   /var/folders/5c/9r7xkl9x6zbc9hvykt4hnpsw0000gn/T/ycmd_50678_stdout_y548jr90.log
--   /var/folders/5c/9r7xkl9x6zbc9hvykt4hnpsw0000gn/T/ycmd_50678_stderr_z31xy6rt.log

Contents of YCM, ycmd and completion engine logfiles

Add let g:ycm_log_level = 'debug' to vimrc, restart Vim, reproduce the
issue, and include link here to a [gist][] containing the entire logfiles for
ycm, ycmd and any completer logfiles listed by :YcmToggleLogs.

ycm_015czata.log
ycmd_51139_stderr_iqtdumfz.log

OS version, distribution, etc.

I have tested on Linux and MacOS. Same behavior

[ApolloBian]

YouCompleteMe: fa92f40

[ApolloBian]

Also, using gd or gD does jump to the __init__ function, so I suppose it is not the problem with my test case.

[bstaletic]

I've noticed this recently too. I'm looking into it.

[bstaletic]

Found the culprit.
The same reason why I opened ycm-core/ycmd#1341

[bstaletic]

Until we figure out how to fix this, use GoToType as that does now what GoTo used to do.

[bstaletic]

Fixed.

[ApolloBian]

@bstaletic Cool! Appreciate the good work!