Thread (6 messages) flat view 6 messages, 3 authors, 2016-12-12

Re: [PATCH 1/3] gitk: turn off undo manager in the text widget

From: Jacob Keller <hidden>
Date: 2016-11-07 22:14:04

On Mon, Nov 7, 2016 at 10:57 AM, Markus Hitter [off-list ref] wrote:
From e965e1deb9747bbc2b40dc2de95afb65aee9f7fd Mon Sep 17 00:00:00 2001
From: Markus Hitter <redacted>
Date: Sun, 6 Nov 2016 20:38:03 +0100
Subject: [PATCH 1/3] gitk: turn off undo manager in the text widget

The diff text widget is read-only, so there's zero point in
building an undo stack. This change reduces memory consumption of
this widget by about 95%.

Memory usage of the whole program for viewing a reference commit
before; 579'692'744 bytes, after: 32'724'446 bytes.
Wow. Nice find!
Test procedure:

 - Choose a largish commit and check it out. In this case one with
   90'802 lines, 5'006'902 bytes.

 - Have a Tcl version with memory debugging enabled. This is,
   build one with --enable-symbols=mem passed to configure.

 - Instrument Gitk to regularly show a memory dump. E.g. by adding
   these code lines at the very bottom:

     proc memDump {} {
         catch {
             set output [memory info]
             puts $output
         }

         after 3000 memDump
     }

     memDump

 - Start Gitk, it'll load this largish commit into the diff text
   field automatically (because it's the current commit).

 - Wait until memory consumption levels out and note the numbers.

Note that the numbers reported by [memory info] are much smaller
than the ones reported in 'top' (1.75 GB vs. 105 MB in this case),
likely due to all the instrumentation coming with the debug
version of Tcl.
Still, this is definitely the lions share of the memory issue.
Additionally, this fix seems much better overall and does not harm any
other aspects of gitk, because we only read the widget so there is as
you mentioned, zero reason to build an undo stack.

Thanks for taking the extra time to find a proper solution to this! I
think it makes perfect sense.
quoted hunk ↗ jump to hunk
Signed-off-by: Markus Hitter <redacted>
---
 gitk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gitk b/gitk
index 805a1c7..8654e29 100755
--- a/gitk
+++ b/gitk
@@ -2403,7 +2403,7 @@ proc makewindow {} {

     set ctext .bleft.bottom.ctext
     text $ctext -background $bgcolor -foreground $fgcolor \
-       -state disabled -font textfont \
+       -state disabled -undo 0 -font textfont \
        -yscrollcommand scrolltext -wrap none \
        -xscrollcommand ".bleft.bottom.sbhorizontal set"
     if {$have_tk85} {
--
2.9.3
Nice that such a simple change results in a huge gain. I think this
makes perfect sense.

Regards,
Jake
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