Subject: Re: bug#77620: thingatpt can be incredibly slow in python-mode buffers

From: Eli Zaretskii <[email-masked]>
Date: Tue, 08 Apr 2025 13:52:44 +0300

> From: JD Smith <[email-masked]>
> Date: Mon, 7 Apr 2025 17:48:49 -0400
> 
> > (/ (car (benchmark-run 10 (thing-at-point 'sexp))) 10)
> 
> 
> Try this test at the start of L8817 in this file (no eglot needed; either python-mode or python-ts-mode is fine, as both show the same issue):
> 
> https://raw.githubusercontent.com/matplotlib/matplotlib/refs/heads/main/lib/matplotlib/axes/_axes.py
> https://raw.githubusercontent.com/matplotlib/matplotlib/refs/heads/main/lib/matplotlib/axes/_axes.py￼
> _axes
> Text Document · 353 KB
> 
> In #77588 this was shown to lead to long intermittent pauses with eglot in large python buffers, but the issue is more general for any packages using thingatpt in python buffers.

The Lisp profile, which seems to point to the likely culprit, is
below.

Maybe kobarity (CC'ed) will have some ideas or suggestions.

         345  89% - ...
         343  89%  - cond
         343  89%   - let
         343  89%    - condition-case
         343  89%     - progn
         343  89%      - save-excursion
         173  44%       - funcall
         173  44%        - thing-at-point--end-of-sexp
         173  44%         - let
         173  44%          - if
         173  44%           - condition-case
         173  44%            - forward-sexp
         173  44%             - python-nav-forward-sexp
         173  44%              - python-nav--forward-sexp
         173  44%               - python-info-statement-ends-block-p
         173  44%                - python-nav-end-of-block
          96  24%                 - python-nav-end-of-statement
          69  17%                  - syntax-ppss
          67  17%                     parse-partial-sexp
          27   7%                  - python-info-line-ends-backslash-p
          27   7%                   - syntax-ppss
          27   7%                      parse-partial-sexp
          76  19%                 - python-nav-beginning-of-block
          76  19%                  - python-nav-backward-block
          76  19%                   - python-nav-forward-block
          75  19%                    - python-syntax-context-type
          75  19%                     - syntax-ppss
          74  19%                        parse-partial-sexp
           1   0%                    - python-nav-beginning-of-statement
           1   0%                       point-marker
           1   0%                   current-indentation
         170  44%       - let
         170  44%        - if
         170  44%         - funcall
         170  44%          - thing-at-point--beginning-of-sexp
         170  44%           - let
         170  44%            - if
         170  44%             - forward-sexp
         170  44%              - python-nav-forward-sexp
         170  44%               - python-nav--forward-sexp
         170  44%                - python-info-statement-ends-block-p
         170  44%                 - python-nav-end-of-block
          95  24%                  - python-nav-end-of-statement
          63  16%                   - syntax-ppss
          62  16%                      parse-partial-sexp
          31   8%                   - python-info-line-ends-backslash-p
          31   8%                    - syntax-ppss
          30   7%                       parse-partial-sexp
           1   0%                     re-search-forward
          75  19%                  - python-nav-beginning-of-block
          75  19%                   - python-nav-backward-block
          75  19%                    - python-nav-forward-block
          72  18%                     - python-syntax-context-type
          72  18%                      - syntax-ppss
          71  18%                         parse-partial-sexp
           2   0%                       re-search-backward
           1   0%                     - python-nav-beginning-of-statement
           1   0%                      - python-info-line-ends-backslash-p
           1   0%                       - syntax-ppss
           1   0%                          syntax-ppss--data
           2   0%  - python-shell-get-process
           2   0%   - python-shell-get-buffer
           2   0%    - seq-some
           2   0%     + seq-do
          32   8%   Automatic GC
           6   1% - command-execute
           6   1%  - call-interactively
           6   1%   - byte-code
           6   1%    - read-extended-command
           6   1%     - read-extended-command-1
           6   1%      - completing-read
           6   1%       - completing-read-default
           6   1%        - read-from-minibuffer
           1   0%           redisplay_internal (C function)
           2   0%   redisplay_internal (C function)