Bug 84635

Summary:	TABLE: Slow layout of large tables (quadratic time)
Product:	LibreOffice	Reporter:	Peter Grimtell <peter.grimtell>
Component:	Writer	Assignee:	Not Assigned <libreoffice-bugs>
Status:	NEW ---	QA Contact:
Severity:	normal
Priority:	medium	CC:	peter.grimtell, stgohi-lobugs, todventtu
Version:	4.2.6.3 release
Hardware:	All
OS:	All
Whiteboard:
i915 platform:		i915 features:
Attachments:	Time to load and lay out document as function of number of rows 6 rows (1 page), 1 second to load 1034 rows (13 pages), 24 seconds to load 2178 rows (26 pages), 62 seconds to load 5871 rows (69 pages), 362 seconds to load 7183 rows (84 pages), 663 seconds to load 9897 rows (116 pages), 1251 seconds to load 10944 rows (128 pages), 1464 seconds to load Perf flame graph for ~10000 rows

Description Peter Grimtell 2014-10-03 15:18:56 UTC

Created attachment 107263 [details]
Time to load and lay out document as function of number of rows

When loading a writer document with a large table (spanning tens or hundreds of pages) it takes a long time to do the layout. The time seems to increase quadratically with the number of table rows.

The tested documents (created by my own code, and passing validation on http://odf-validator.rhcloud.com/) use a small font (4 pt), so the amount of text that fits in each page is large, but the seeming O(n^2) trend is worrying.

Comment 1 Peter Grimtell 2014-10-03 15:21:51 UTC

Created attachment 107264 [details]
6 rows (1 page), 1 second to load

Comment 2 Peter Grimtell 2014-10-03 15:23:08 UTC

Created attachment 107265 [details]
1034 rows (13 pages), 24 seconds to load

Comment 3 Peter Grimtell 2014-10-03 15:23:45 UTC

Created attachment 107266 [details]
2178 rows (26 pages), 62 seconds to load

Comment 4 Peter Grimtell 2014-10-03 15:24:14 UTC

Created attachment 107267 [details]
5871 rows (69 pages), 362 seconds to load

Comment 5 Peter Grimtell 2014-10-03 15:24:45 UTC

Created attachment 107268 [details]
7183 rows (84 pages), 663 seconds to load

Comment 6 Peter Grimtell 2014-10-03 15:25:27 UTC

Created attachment 107269 [details]
9897 rows (116 pages), 1251 seconds to load

Comment 7 Peter Grimtell 2014-10-03 15:25:53 UTC

Created attachment 107270 [details]
10944 rows (128 pages), 1464 seconds to load

Comment 8 Peter Grimtell 2014-10-03 15:32:43 UTC

Created attachment 107271 [details]
Perf flame graph for ~10000 rows

Comment 9 Peter Grimtell 2014-10-03 15:38:53 UTC

One thing I've noted is that LO first overestimates the number of pages (e.g. showing page count as 190 instead of 116) for a long time until the layout has been completed.

My computer specs: i7-3820@3.6GHz, 16 GB RAM, SSD.

Comment 10 Beluga 2014-11-14 18:44:18 UTC

I tested three of them. 4.4 alpha seems to be a lot better.

1034 rows (13 pages): 10 secs
5871 rows (69 pages): 83 secs
10944 rows (128 pages): 125 secs

Win 7 64-bit Version: 4.4.0.0.alpha2+
Build ID: b021b5983c62e266b82d9f0c5c6d8d8900553827
TinderBox: Win-x86@39, Branch:master, Time: 2014-11-12_01:10:08

i7-2640M@2.80Ghz, 8 GB RAM (with an Ubuntu VM running with 4 GB allocated to it of the 8 GB), no SSD.

Comment 11 A (Andy) 2014-11-14 20:57:38 UTC

Reproducible with LO 4.3.3.2, Win 8.1 (i3, 1.8GHz, 4GB RAM)

When trying to load the document with 1,034 rows it took for me more than 20 seconds to load it and the status bar was all the time flickering.

@Beluga: Thanks for also testing it on LO 4.4 and it is great to hear that there it is already faster.  I don't know if there can maybe also be made further improvements already for LO 4.3?

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