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  1. #11
    Join Date
    Nov 2015
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    21

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    After experimenting a bit more with BC4 I found the reason of its slow startup and a stack trace is below. Basically, it has to do with computing font metrics and uploading text glyphs to the X server which is quite slow. This only happens if you start BC4 without asking for a diff. When starting with a diff request (two files as arguments on command line) for some reason all this process is skipped and the diff is shown in less than 2 sec.

    writev(6, [{"\212\24O\0A\0@\3\1\0\0\0V\0\0\0\t\0\10\0\1\0\10\ 0\6\0\0\0\0\0\0\0"..., 16240}, {"\0\0\0\0\0\0\0\0005\23\3\23\305\232g\232\377\373 \345\373\364\37
    7\377\377\340\324\337\324\340\375\365\375"..., 440}, {"", 0}], 3) = 16680
    > /usr/lib64/libc-2.22.so(__writev_nocancel+0x24) [0xf86ed]
    > /usr/lib64/libxcb.so.1.1.0(_xcb_conn_wait+0x34b) [0xa57b]
    > /usr/lib64/libxcb.so.1.1.0(_xcb_out_send+0x51) [0xa961]
    > /usr/lib64/libxcb.so.1.1.0(xcb_writev+0x45) [0xa9e5]
    > /usr/lib64/libX11.so.6.3.0(_XSend+0x16e) [0x40c7e]
    > /usr/lib64/libXrender.so.1.3.0(XRenderAddGlyphs+0x1f8) [0x2fd8]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QFontEngineX11FT::uploadGlyphToS erver(QFontEngineFT::QGlyphSet*, unsigned int, QFontEngineFT::Glyph*, _XGlyphInfo*, int) const+0x54)
    [0x4ea5c4]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QFontEngineFT::loadGlyph(QFontEn gineFT::QGlyphSet*, unsigned int, QFixed, QFontEngine::GlyphFormat, bool) const+0x989) [0x4f39c9]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QFontEngineFT::recalcAdvances(QG lyphLayout*, QFlags<QTextEngine::ShaperFlag>) const+0xc3) [0x4f4293]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(hb_getAdvances(HB_Font_*, unsigned int const*, unsigned int, int*, int)+0x111) [0x4231c1]
    > /usr/lib64/qt4/libQtCore.so.4.8.7(HB_HeuristicPosition+0x36) [0xf9026]
    > /usr/lib64/qt4/libQtCore.so.4.8.7(HB_OpenTypePosition+0x2a8) [0xfaea8]
    > /usr/lib64/qt4/libQtCore.so.4.8.7(HB_ShapeItem+0x23) [0xffab3]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QTextEngine::shapeTextWithHarfbu zz(int) const+0x7c7) [0x453ec7]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QTextEngine::shapeText(int) const+0x72) [0x454812]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QTextEngine::shape(int) const+0x95) [0x454b45]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QTextEngine::width(int, int) const+0x29f) [0x45894f]
    > /usr/lib64/qt4/libQtGui.so.4.8.7(QFontMetrics::width(QString const&, int, int) const+0x1ef) [0x43158f]
    > /usr/lib64/qt4/libQt4Pas.so.5.2.5(QFontMetrics_width+0x6d) [0x14b28d]
    Last edited by mikko; 19-Nov-2015 at 03:48 PM.

  2. #12
    Join Date
    Oct 2007
    Location
    Madison, WI
    Posts
    11,376

    Default

    Thanks for this info dump. I'll pass it on to our Linux developer and see what feedback he has.
    Aaron P Scooter Software

  3. #13
    Join Date
    Nov 2015
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    21

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    Thanks, hopefully he finds a cure for this problem. Meanwhile, I found a BC4 issue when comparing large files and reported that in another thread.
    /M

  4. #14
    Join Date
    Oct 2007
    Location
    Madison, WI
    Posts
    11,376

    Default

    Hello,

    Try running qtconfig from your command line and switching to a different or default theme. You may also need to reboot to troubleshoot and make certain the theme is applied.

    If qtconfig is not installed, use apt-get install qtconfig-qt4 to install it.
    Aaron P Scooter Software

  5. #15
    Join Date
    Nov 2015
    Posts
    21

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    I did that, tried them all with various fonts. The UI style does change, no need for reboot but BC4 behaves the same, much faster to start and do a diff than start the empty home view...

    /M

  6. #16
    Join Date
    Oct 2007
    Location
    Madison, WI
    Posts
    11,376

    Default

    I tried setting up a Fedora 23 64bit machine with updates applied, and glibc 2.22.5.fc23, but did not hit any slowdown or difference in startup between launching bcompare and launching bcompare a.txt b.txt

    This may come down do how you've customized your OS. Is there any info you could give to help setup this type of environment? Or is it possible for you to test on a standard Fedora 23 setup?
    Aaron P Scooter Software

  7. #17
    Join Date
    Nov 2015
    Posts
    21

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    Thanks for the verification. Besides giving you access to the actual machine it's not possible to provide a simple diff with official Fedora 23. I guess I'll have to examine such standard FC23 machine and see if I can spot the reasons... looks to be a Qt font loading/configuration issue...

    I do use the xfce4 window manager and desktop, I have 1.17.4 server, the same 2.22.5 glibc but nearly all software is built for source locally to better integrate with everything.

    /M

  8. #18
    Join Date
    Nov 2015
    Posts
    21

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    Found one clear reason for extra slowness when starting in the home view, the Web Resources Panel. I had it as default open, when I have it closed startup times improve from ~4sec to ~2sec. As this conversation has been going in the wrong thread for some time, I'll open a new thread in BC4 forum

    /M

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