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List:       konsole-devel
Subject:    Re: [Konsole-devel] Review Request: patch to reduce memory usage
From:       mick22 () gmx ! at
Date:       2009-06-17 23:22:24
Message-ID: 20090617232224.29327.49070 () localhost
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http://reviewboard.kde.org/r/802/
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(Updated 2009-06-17 16:22:24.013010)


Review request for Konsole.


Changes
-------

Yet another version of the patch. As it turned out during the discussion of bug \
176974, the data size of konsole seldom shrinks (probably due to heap fragmentation), \
even if the history is cleared or a tab is closed. This might seem like a memory leak \
to some users, even though valgrind does not show leaks in the history code.

This version of the patch uses a simple custom memory pool (implemented as a list of \
mmap'ed blocks) to allocate memory for history lines.

To keep things simple, the two types of history lines of previous patch versions \
(single- and multi-color) are no longer used, as mem allocation is cheaper now \
anyway.


Summary
-------

Here's a patch that drastically reduces mem usage when a fixed size history is
used:
- new history storage type "HistoryTypeQList"  (QList-based) set as replacement for \
                HistoryTypeBuffer
- compact storage for history lines

History lines are stored as an array of chars when possible (i.e. when
color and rendition flag of all characters in the line are equal). 2 bytes per \
character + overhead

When not (easily) possible, it falls back to the current way of storing history lines \
(array of QVector<Character>). 11 bytes per character + overhead

Memory usage has been cut down from about 171MB to 55MB for a konsole process
with 5 tabs, 30000 lines scrollback, 65 chars per line.

Update:
As suggested in https://bugs.kde.org/show_bug.cgi?id=176974#c20, a formatting array \
has been introduced in v2 of the patch. The CompactHistoryLine class can now handle \
single- and multi-color history lines. This replaces v1 of the patch where 2 separate \
classes were used.


This addresses bug 176974.
    https://bugs.kde.org/show_bug.cgi?id=176974


Diffs (updated)
-----

  /trunk/KDE/kdebase/apps/konsole/src/Character.h 981222 
  /trunk/KDE/kdebase/apps/konsole/src/History.h 981222 
  /trunk/KDE/kdebase/apps/konsole/src/History.cpp 981222 
  /trunk/KDE/kdebase/apps/konsole/src/SessionController.cpp 981222 
  /trunk/KDE/kdebase/apps/konsole/src/SessionManager.cpp 981222 

Diff: http://reviewboard.kde.org/r/802/diff


Testing
-------

reasonably tested 


Thanks,

mick22

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