Bug 291405

Summary:

perf issues with rowspan="0" on huge complex tables

Product:

WebKit

Reporter:

Karl Dubost <karlcow>

Component:

Tables

Assignee:

Karl Dubost <karlcow>

Status:

NEW

Severity:

Normal

CC:

webkit-bug-importer, zalan

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

Bug Depends on:

185341

Bug Blocks:

Attachments:

Description	Flags
simple table 3x3 no rowspan	none
simple 3x3 with rowspan 0 in the first column	none
rowspan=2 testcase	none
rowspan=0 not removing cells	none
rowspan=2 with two tbody	none
15x3 table with many rowspan	none
93 rowspans	none
1381 rowspans of different nature with complex tables	none

Karl Dubost

Reported 2025-04-10 21:21:41 PDT

Created attachment 474888 [details] simple table 3x3 no rowspan In Bug 185341, the layout for rowspan="0" was fixed. It is working well for simple table but creates performance issues for huge tables with weird and incorrect rowspans. It needs to be improved.

Attachments
simple table 3x3 no rowspan (510 bytes, text/html) 2025-04-10 21:21 PDT, Karl Dubost	no flags	Details
simple 3x3 with rowspan 0 in the first column (513 bytes, text/html) 2025-04-10 21:22 PDT, Karl Dubost	no flags	Details
rowspan=2 testcase (525 bytes, text/html) 2025-04-10 21:23 PDT, Karl Dubost	no flags	Details
rowspan=0 not removing cells (537 bytes, text/html) 2025-04-10 21:24 PDT, Karl Dubost	no flags	Details
rowspan=2 with two tbody (807 bytes, text/html) 2025-04-10 21:25 PDT, Karl Dubost	no flags	Details
15x3 table with many rowspan (1.30 KB, text/html) 2025-04-10 21:26 PDT, Karl Dubost	no flags	Details
93 rowspans (4.21 KB, text/html) 2025-04-10 21:30 PDT, Karl Dubost	no flags	Details
1381 rowspans of different nature with complex tables (44.31 KB, text/html) 2025-04-10 21:35 PDT, Karl Dubost	no flags	Details
View All Add attachment proposed patch, testcase, etc.

Karl Dubost

Comment 1 2025-04-10 21:22:54 PDT

Created attachment 474889 [details] simple 3x3 with rowspan 0 in the first column

Karl Dubost

Comment 2 2025-04-10 21:23:52 PDT

Created attachment 474890 [details] rowspan=2 testcase

Karl Dubost

Comment 3 2025-04-10 21:24:29 PDT

Created attachment 474891 [details] rowspan=0 not removing cells

Karl Dubost

Comment 4 2025-04-10 21:25:06 PDT

Created attachment 474892 [details] rowspan=2 with two tbody

Karl Dubost

Comment 5 2025-04-10 21:26:12 PDT

Created attachment 474893 [details] 15x3 table with many rowspan

Karl Dubost

Comment 6 2025-04-10 21:30:01 PDT

Created attachment 474894 [details] 93 rowspans This one displays but starts to be slow. It has 4 lines with 93 rowspan of different natures with different columns. It's where the complexity starts to kick in. It displays faster in Chrome/Firefox (but probably also slower than expected.) I have a patch which improves the speed.

Karl Dubost

Comment 7 2025-04-10 21:35:19 PDT

Created attachment 474895 [details] 1381 rowspans of different nature with complex tables Some cols and rows are different There are 1281 rowspans on 62 rows with 1746 cells 41 rowspan="1" 20 rowspan="2" 1319 rowspand="0" 366 cell without rowspan This is crazy but this has hit a real case not accessible on the public web. The layout doesn't really make sense. BUT Firefox and Chrome managed to display it. This will freeze Safari 18.4

Karl Dubost

Comment 8 2025-04-10 21:36:13 PDT

<rdar://146056348>

Karl Dubost

Comment 9 2025-04-10 21:50:11 PDT

Pull request: https://github.com/WebKit/WebKit/pull/43940

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