I was wondering why kill-emacs emacs takes over a minute and after some
profiling I found out that the call to org-persist-write-all takes long when
pp-use-max-width is set to t and pp-max-width is also set (in my case to t, the
window-width), which enables line folding in pp. The pp-call happens in
org-persist--write-elisp-file when it is called by org-persist-write:index with
the pp-parameter set to t. Maybe it's clearer with the following excerpt of my
CPU-profile:
38009 96% - org-persist-write-all
38009 96% - org-persist-write
37703 95% - mapcar
37703 95% - #<compiled 0x42bf9b75c0e2209>
37703 95% - org-persist-write:index
37703 95% - org-persist--write-elisp-file
37703 95% - pp
37703 95% - pp-to-string
37703 95% - pp-emacs-lisp-code
37687 95% + pp--insert-lisp
Setting pp-use-max-width to nil made the function call almost instantanteous.
I had enabled pp-use-max-width in the past when pretty-printing the results of
interactive elisp sessions (like pp-eval-last-sexp). I didn't think this would
affect how other packages would save their data and I didn't expect this would
result in such a performance hit. Possibly this is not an issue with org-mode
or pp but just my own mistake of not being aware that pp is used as a library
by other packages and thus customizing its behaviour has global effects.
Not sure if the org mailing list is the best place to report this observation.
What org could do is to use a let-binding to temporarily set pp-use-max-width
to nil to disable line folding. Or do you think that some users might care that
their cache files are formatted prettily according to their customization
options?
If you think this is not an issue with org-mode, maybe I/we could forward this
to the pp-maintainers, as it's in emacs core possibly to emacs-devel? I think
at least a warning in the variable documentation about performance hits might
have been helpful.
Best regards,
Michael Eliachevitch
