Hi Everybody,
I come from a Delphi background. A while ago the FastMM memory allocator was adopted by the compiler team because it gave very good results for small allocations. It's not quite SLAB - it only looks at the size, not the type of object, since all Delphi objects are initialised to zeroes. I recently needed to optimise XML handling in a Qt application server, and assumed C++ would have something similar. I was surprised to find that a VS C++ version was not available, and that changing the allocator requires nasty run-time patching of linker addresses (?). In the end I chose Qt 4.8.1 QXmlStreamWriter(QString *). The QByteArray version seemed the logical choice - but since the API only uses QString, each call resulted in temporaries being allocated and disposed. It seems QString is crying out for an appendLatin1(const char *, int len) that re-allocates the unicode array if necessary, and then does the latin1 conversion without creating a temporary. Doing a single toUtf8 at the end is also better than calling it a million times. Another big gain comes from not using literal strings for the element and attribute tags in loops - create static QStrings, so the latin1 conversion only happens once. To Jason: Pre-creating all of the gui's seems extreme? Doesn't it waste a lot of memory if only a small number of dialogs are open at any time? Also, unless the dialogs are all static labels, won't populating the controls when the dialog opens cause allocations? Regards, Tony
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