Re: Compiled format specs in .newsrc.eld?

[Jesper Harder <harder@ifa.au.dk>]

jas@extundo.com (Simon Josefsson) writes:

> Jesper Harder <harder@ifa.au.dk> writes:
>
>> I wasn't really sure whether the manual or the code was wrong about saving
>> format specs -- I can think of two good reasons for not saving them:
>>
>> * It doesn't really matter.
>> * Byte-code isn't portable between Emacs and XEmacs.
>
> Yup.  Is the manual correct below?  

I think this part is wrong:

 | This will result in the new specs being byte-compiled, and you'll
 | get top speed again.  Gnus will save these compiled specs in the
 | `.newsrc.eld' file.

It's true that if you run `gnus-compile', Gnus will save the byte
compiled values in newsrc.eld.  But if I

* Run `gnus-compile'
* Quit Gnus

then at this stage the byte-compiled values are in .newsrc.eld.  
But if I

* Start Gnus again, and quit.

then the byte-compiled values in newsrc.eld have been replaced with the
uncompiled values.  

So, it appears that if you want the specs to be byte-compiled, you need
(gnus-compile) in .gnus.  This is probably a bug -- but I don't
understand what's going on.

> Does Gnus byte-compile format-specs by default internally?

I'm not sure any more.  I was probably wrong, because I looked at the
global value of `gnus-summary-line-format-spec', but I think the buffer
local value is actually used when generating the summary-buffer.

> Perhaps we should remove gnus-format-specs from gnus-variable-list
> completely.  If there is no speed gain in M-x gnus-compile I vote for
> removing it.

I think someone else should also try to verify whether `gnus-compile'
makes a big difference.  The difference I'm measuring is the smaller
than the variance.  But I'm a bit suspicious about the results -- I
would have expected it to make a much bigger difference.

BTW, I'm using this method to profile it -- it times how long it takes
to show the oldest 10.000 messages from comp.text.tex (I don't do expiry
on the server, so they're always the same):

(defun gnus-profile ()
  (interactive)
  (let (t1 t2 no (sum 0) (avg 0))
    (gnus)
    (sit-for 1)
    (dotimes (i 5)
      (gnus-group-jump-to-group "comp.text.tex")
      (garbage-collect)
      (sit-for 1)
      (setq t1 (float-time))
      (gnus-topic-select-group -10000)
      (setq t2 (float-time))
      (add-to-list 'no (- t2 t1))
      (sit-for 1)
      (gnus-summary-exit)
      (sit-for 1))
    (gnus-group-exit)
    (switch-to-buffer (get-buffer-create "gnus-profile"))
    (dolist (i no)
      (insert (format "%f " i))
      (setq sum (+ sum i)))
    (insert (format "\nSum: %f \n" sum))
    (setq avg (/ sum (length no)))
    (insert (format "Avg: %f \n" avg))
    (insert (format "Var: %f \n" (varians no)))))

(defun varians (d)
  (let ((avg (/ (apply '+ d) (length d)))
	(tmp 0))
    (dolist (x d)
      (incf tmp (expt (- x avg) 2)))
    (sqrt (/ tmp (- (length d) 1)))))