bug#20285: 25.0.50; blink-cursor-mode sometimes stops blinking

[Tassilo Horn]

Eli Zaretskii <eliz@gnu.org> writes:

>> Then I switched to some large latex buffer, did M-: (setq
>> th/redisplay-count 0), and then started compiling that document to
>> generate some load.  Then I waited for exactly one minute in which there
>> has been at least one phase of almost 10 seconds with the cursor being
>> invisible on the screen before getting the value of th/redisplay-count.
>> 
>> And the value is seven hundred something every time I test.  That's more
>> than 10 redisplays of the selected window per second!  I didn't do
>> anything in that one minute so there shouldn't have been a reason for
>> redisplay to kick in except for the blinking cursor.  And that would
>> suggest 120 redisplays.
>
> Can you please elaborate as to how you arrived to these numbers?  I
> fail to follow your line of reasoning; perhaps it's too early and I
> don't yet have enough caffeine in my blood.  E.g., how do you deduce
> from "seven hundred something" that there were more than 10 redisplays
> per second?

Well, I set the counter to zero and then measured ~60 seconds.  In that
time, there were 783 redisplays IIRC.  That gives an average of 13.05
redisplays per second.

>> Of course, it's still possible that during the 10 seconds where the
>> cursor was invisible on the screen there hasn't been a redisplay of
>> the selected window, but how can I know?
>
> If your Emacs is configured with --enable-checking='yes,glyphs', then
> you can invoke "M-x trace-redisplay RET", and see every entry to
> redisplay_internal announced on stderr.

Ok, I'll try that out.  I'll also try out the 0.53 interval to check if
that cures the issue for me, too.

Bye,
Tassilo