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bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 1
From: |
Dmitry Antipov |
Subject: |
bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006 |
Date: |
Mon, 02 Dec 2013 14:45:25 +0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 |
On 12/01/2013 08:31 PM, Eli Zaretskii wrote:
Dmitry, can you please look into this? I'm not familiar enough with
the font stuff, so I don't see how was the font-spec and its
font-entities stored in the font cache supposed to be referenced from
some other Lisp object, to make sure they are marked and not GC'ed.
It should be easy - just use this:
=== modified file 'src/alloc.c'
--- src/alloc.c 2013-12-01 22:33:13 +0000
+++ src/alloc.c 2013-12-02 09:32:55 +0000
@@ -5731,7 +5731,18 @@
eassert (!VECTOR_MARKED_P (ptr));
VECTOR_MARK (ptr); /* Else mark it. */
if (size & PSEUDOVECTOR_FLAG)
- size &= PSEUDOVECTOR_SIZE_MASK;
+ {
+ size &= PSEUDOVECTOR_SIZE_MASK;
+ if (PSEUDOVECTOR_TYPEP (&ptr->header, PVEC_FONT))
+ {
+ Lisp_Object tmp;
+ XSETFONT (tmp, ptr);
+ if (FONT_SPEC_P (tmp))
+ fprintf (stderr, "mark font-spec\n");
+ else if (FONT_ENTITY_P (tmp))
+ fprintf (stderr, "mark font-entity\n");
+ }
+ }
and set breakpoints to fprintf(). I tried this and see that font-spec
objects can be referenced from face caches:
(gdb) bt 3 full
#0 mark_vectorlike (ptr=0x13178b8) at ../../trunk/src/alloc.c:5741
tmp = {i = 20019389}
size = 13
i = 20019389
#1 0x00000000005ec050 in mark_object (arg=...) at ../../trunk/src/alloc.c:6084
ptr = 0x13178b8
pvectype = 15
obj = {i = 20019384}
cdr_count = 0
#2 0x00000000005eb92b in mark_face_cache (c=0x15049b0) at
../../trunk/src/alloc.c:5839
face = 0x18d2050
i = 2
j = 15
(More stack frames follow...)
I.e. (struct face *)0x18d2050 has font-spec object in lface[15].
But the most of font-spec and font-entity objects are referenced via
staticpro'ed globals Vfontset_table and ft_face_cache. For example:
(gdb) bt 16
#0 mark_vectorlike (ptr=0x129a288) at ../../trunk/src/alloc.c:5741
#1 0x00000000005ec050 in mark_object (arg=...) at ../../trunk/src/alloc.c:6084
#2 0x00000000005eb5f0 in mark_vectorlike (ptr=0x1296428) at
../../trunk/src/alloc.c:5752
#3 0x00000000005ec050 in mark_object (arg=...) at ../../trunk/src/alloc.c:6084
#4 0x00000000005eb5f0 in mark_vectorlike (ptr=0x129a4d0) at
../../trunk/src/alloc.c:5752
#5 0x00000000005ec050 in mark_object (arg=...) at ../../trunk/src/alloc.c:6084
#6 0x00000000005eb725 in mark_char_table (ptr=0x1788060) at
../../trunk/src/alloc.c:5779
#7 0x00000000005eb717 in mark_char_table (ptr=0x12094d0) at
../../trunk/src/alloc.c:5776
#8 0x00000000005eb717 in mark_char_table (ptr=0x13e2578) at
../../trunk/src/alloc.c:5776
#9 0x00000000005eb717 in mark_char_table (ptr=0xd85188) at
../../trunk/src/alloc.c:5776
#10 0x00000000005ec02c in mark_object (arg=...) at ../../trunk/src/alloc.c:6069
#11 0x00000000005eb5f0 in mark_vectorlike (ptr=0xd85080) at
../../trunk/src/alloc.c:5752
#12 0x00000000005ec050 in mark_object (arg=...) at ../../trunk/src/alloc.c:6084
#13 0x00000000005eac4b in Fgarbage_collect () at ../../trunk/src/alloc.c:5489
#14 0x0000000000563500 in maybe_gc () at ../../trunk/src/lisp.h:4462
#15 0x000000000060ec3e in Ffuncall (nargs=2, args=0x7fffffff0790) at
../../trunk/src/eval.c:2756
(gdb) bt 16 full
...
#13 0x00000000005eac4b in Fgarbage_collect () at ../../trunk/src/alloc.c:5489
nextb = 0x0
stack_top_variable = 0 '\000'
i = 1491
message_p = false
count = 140
start = {tv_sec = 1385977872, tv_nsec = 656653658}
retval = {i = 13914818}
tot_before = 0
...
(gdb) p staticvec[1491]
$8 = (Lisp_Object *) 0xd25cb0 <Vfontset_table>
In any case, it seems like they are never marked on Windows, because
if I set a breakpoint in the line marked below:
/* If font-spec is not marked, most likely all font-entities
are not marked too. But we must be sure that nothing is
marked within OBJ before we really drop it. */
for (i = 0; i < size; i++)
if (VECTOR_MARKED_P (XFONT_ENTITY (AREF (XCDR (obj), i))))
break;
if (i == size) <<<<<<<<<<<<<<<<<<<<<
drop = 1;
}
with a condition i != size, that breakpoint never breaks.
The best way to hit this breakpoint is to run something like:
(defun bloat-font ()
(interactive)
(let ((fonts (x-list-fonts "*")))
(while fonts
(condition-case nil (set-frame-font (car fonts)) (error nil))
(setq fonts (cdr fonts))
(redisplay))))
(This is X-specific; I believe there should be a similar MS-Windows method).
Subtle "triangle example" works just fine for me (with default font used by
GTK3 build and 'emacs -Q' at least).
Also I'm curious how to reproduce this issue with X. In particular, how to
find a font so "heavy" that an attempt to load it creates a lot of Lisp data
(hundreds Kbytes, enough to reach gc_cons_threshold each time)?
Dmitry
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Eli Zaretskii, 2013/12/01
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006,
Dmitry Antipov <=
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Dmitry Antipov, 2013/12/02
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Eli Zaretskii, 2013/12/02
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Dmitry Antipov, 2013/12/03
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Eli Zaretskii, 2013/12/03
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Dmitry Antipov, 2013/12/03
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Eli Zaretskii, 2013/12/04
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Dmitry Antipov, 2013/12/05
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Eli Zaretskii, 2013/12/05
- bug#15876: 24.3.50; Highly degraded performance between rev 114715 and 115006, Dmitry Antipov, 2013/12/11