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Re: NS port: How to debug excessive garbage collection?
From: |
Keith David Bershatsky |
Subject: |
Re: NS port: How to debug excessive garbage collection? |
Date: |
Sun, 14 Apr 2019 12:46:28 -0700 |
The attched patch (debug_mwe_001.diff) is a minimal working example that
demonstrates the issue on all three platforms (X11, W32, NS) using the GUI
version of Emacs built from the master branch as of 04/08/2019
(a038df77de7b1aa2d73a6478493b8838b59e4982).
The snippet that I am pasting and evaluating in the minibuffer is as follows:
(progn
(find-library "simple")
(fundamental-mode)
(blink-cursor-mode -1)
(global-eldoc-mode -1)
(setq timer-list nil
timer-idle-list nil
crosshairs t))
Here are Youtube links to screen recordings of the minimal working example on
all three platforms:
NS (screen recording): https://youtu.be/4IzXfP2j2GY
X11 (screen recording): https://youtu.be/zrRH72qdmx0
W32 (screen recording): https://youtu.be/cfIG4fbkesY
MINIMAL WORKING EXAMPLE:
1. Imaginary / Pretend: We imagine that all fake cursors are erased at the
outset of update_window while w->current_matrix is still valid; i.e., before
scrolling_window does its thing.
2. The master cache of fake cursors (w->ch_cache) is set to Qnil.
3. Imaginary / Pretend: We imagine .... As to the rows in the
w->desired_matrix that must be updated with update_text_area, we draw fake
cursors immediately after draw_glyphs finishes updating the row. As we are
laying fake cursors, we use a temporary cache (w->mc_temp_cache) to store the
relevant data so that we can redraw any fake cursors that get erased because
they are left/right_overwritten as determined by draw_glyphs. Once the row has
been updated with fake cursors, we set the termporary cache (w->mc_temp_cache)
to Qnil and we set the master cache with the new data -- appending new data if
the cache is non-nil.
4. As to all remaining rows that are not updated with update_text_area (which
uses w->desired_matrix), we use the w->current_matrix and draw/cache the fake
cursors using the same approach as mentioned in the preceding step; i.e., a
temporary cache (w->mc_temp_cache) so that we can fix any fake cursors that got
left/right_overwritten and then that cache is set to Qnil and the master cache
(w->mc_cache) is updated.
In the above minimal working example, the window Lisp_Object caches are rather
simple:
'((make_fixnum (1))
(make_fixnum (2))
(make_fixnum (3))
...
(make_fixnum (99)))
debug_mwe_001.diff
Description: application/diff