On Tuesday, 24 April 2018 22:46:43 PDT Maurice Kalinowski wrote: > > On Tuesday, 24 April 2018 09:39:37 PDT Julien Cugnière wrote: > > > 2018-04-24 17:52 GMT+02:00 Thiago Macieira <thiago.macie...@intel.com>: > > > > On Tuesday, 24 April 2018 07:39:08 PDT Konstantin Tokarev wrote: > > > >> If your serialized data is intended to be read by Qt applications > > > >> only, QDataStream may be a good choice > > > > > > > > Also slow. > > > > > > > > Binary QJsonDocument is the fastest, followed closely by QCborValue > > > > (new in 5.12). > > > > > > Out of curiosity, what makes QDataStream slow? From your other > > > > comment > > > > > on QBuffer, it sounds like it might be related to the QIODevice > > > interface. Does that mean it's impossible to get best performance > > > through QIODevice, because of some design flaw? Or is there something > > > else that makes QDataStream and QBuffer slow? > > > > I benchmarked the full result, but didn't investigate what makes > > QDataStream slow. But it suffers from the same problem that > > QXmlStreamWriter does: it uses a QBuffer to write to a QDataStream (see > > [1] > > and [2]). QCborStreamWriter does the same, actually -- I've only fixed > > QCborStreamReader to bypass it. > > [Maurice Kalinowski] > > Hey, > > Would you still have these benchmarks somewhere? I am currently playing > around with various serialization ways as well, and so far came to > different conclusions. Probably because of using different means, but would > still like to see how you approached it for plain text json.
I posted to dev in the CBOR thread a few months ago. Basically, the procedure was: 1) find a large-ish JSON file as a test seed 2) make it bigger (replicate it 100x or more in an array) -- I used something like 60 MB in binary JSON form, which is just about half the maximum 3) use the examples/corelib/serialization/convert tool[1] to convert to other formats 4) use the same tool with the "null" output to benchmark reading[2] 5) use the tool with binary JSON as source to benchmark writing I basically benchmarked using Linux's perf. The stat subcommand for overall timings, but using perf record + perf annotate to analyse where the issues were. [1] https://codereview.qt-project.org/217410. The tool should work for all other formats right now if you just remove "cborconverter.cpp" from the .pro file. [2] I modified main.cpp to read and write using QBuffer instead of QFile to minimise the cost of QIODevice. -- Thiago Macieira - thiago.macieira (AT) intel.com Software Architect - Intel Open Source Technology Center _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
