[Libreoffice-bugs] [Bug 69069] [EDITING, VIEWING] 100% CPU while Scrolling and copying Columns

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=69069

Buovjaga <todventtu at suomi24.fi> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |erack at redhat.com
            Version|3.6.3.2 release             |3.6.0.4 release
           Keywords|bibisectRequest             |bibisected

--- Comment #14 from Buovjaga <todventtu at suomi24.fi> ---
I bibisected on Linux with 43all for the horizontal scroll in werte sheet and
it blamed this range:
https://cgit.freedesktop.org/libreoffice/core/log/?qt=range&q=18e6e7d929c2be209407ed2e56b8ec4d5e6c4900...9ca02a663c3eee2698eb360dd5dc7afb1951e743

It was a bit challenging because the difference of CPU hammering is not very
big.

Guessing, the reason could be
https://cgit.freedesktop.org/libreoffice/core/commit/?id=435c117c1c684d4603f557ed821c1fd5ee057086

commit  435c117c1c684d4603f557ed821c1fd5ee057086 (patch)
tree    ef8ebdfb4cb970999adcc3416b967511a53af490
parent  904763b1134bdd84a4e64de1e037da5cac192f27 (diff)
some optimization of ScAttrArray::GetLastVisibleAttr()
Method assumed that not much attribution happens below data and started from
the end of attribution, in the case of not much attribution it worked fine.
For the case of many differently formatted areas with a sufficiently large
area of visibly equal attribution near data end it was a bottle neck looping
over unnecessarily many comparisons. Start at data end instead. For the case
of not much attribution it doesn't really matter, and for the case of no
sufficiently large area below data end it doesn't matter at all and compares
the same number of entries. The drawback would be a large area near
attribution end with many small areas between data end and the large area.

Observed with test case of fdo#46160

Adding Cc: to Eike Rathke

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