Re: ccomplete#Complete very slow on large tags file

Hi Tony,

On 01/04/20 07:26PM, Tony Mechelynck wrote:
> On Wed, Apr 1, 2020 at 7:15 PM Pratyush Yadav <me@yadavpratyush.com> wrote:
> >
> > Hi,
> >
> > I am using the built-in ccomplete#Complete omnifunc for tags-based
> > completion. It works pretty well with a small or medium sized project.
> > But on larger projects like Linux or U-Boot, the tags file is pretty big
> > (~650k lines/70 for U-Boot and ~4.8 mil lines/630MB for Linux).
> >
> > On these projects, especially Linux, if I use ccomplete, completion
> > takes a huge amount of time. And since the completion is synchronous,
> > vim just freezes up for that time and I have to wait for the completion
> > results to show up. On Linux the wait times can go more than a minute on
> > my modest quad core 4th gen i7 and a SATA SSD.
> >
> > So, I intend to set aside some time and try to speed up the completion
> > and make it asynchronous. I haven't read or written much vimscript so I
> > don't expect it to be easy or quick. So before I do that, I'd like to
> > know if anyone here attempted this before.
> >
> > If someone did succeed, could you please point me to the optimized
> > version? If someone tried but failed, could you please let me know where
> > you had trouble? Is it that the ctags format just not suitable for large
> > projects? Is there some limitation with vim that makes it impossible? Is
> > it something else entirely?
> >
> > --
> > Regards,
> > Pratyush Yadav
>
> The Vim tags file is pretty large, but how is your tags file built? In
> particular, is it case-fold-sorted? If your Vim is built with
> +tag_binary (nowadays it always is, if yours isn't you need a newer
> model), and 'tagbsearch' is on (which is the default), then finding a
> tag in an unsorted tags file uses linear time, in a case-folded sorted
> tags file it uses logarithmic time, which is much faster, especially
> for large tags files.

Yes, the tags file is sorted and vim is built with +tag_binary and
'tagbsearch' is on. The tags file wasn't case-folded sorted, but I tried
with that too and I see similar performance.

Anyway, just to remove any potential confusion, jumping to tags via
'CTRL-]' is blazing fast. So is listing all alternatives with 'g]'. Does
ccomplete use the same mechanism for searching tags file as those two?
If so, then I wonder why it is so much slower.

Also if I have a struct foo, doing something like 'foo->' takes a huge
amount of time because I think there is no other way to get a list of
members of a struct without a linear search, but that is a different
problem entirely.

--
Regards,
Pratyush Yadav

--
--
You received this message from the "vim_use" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php

---
You received this message because you are subscribed to the Google Groups "vim_use" group.
To unsubscribe from this group and stop receiving emails from it, send an email to vim_use+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/vim_use/20200401180220.ffuizuelijlyd3dr%40yadavpratyush.com.