Thomas, May be related to the dependency scanning update. Previously SCons didn't find cross-language dependencies including those between CPP/QT, CPP/SWIG, etc; thus, previous dependency graphs would be incomplete.
This will mean slightly more scanning time and possibly less parallelization in your builds, since I suspect that there have been race conditions previously. Generally, SCons execution time is a measure of time spent in Builders/Actions. V/R, William On Mon, Apr 11, 2016 at 12:14 PM, Thomas Berg <merlin...@gmail.com> wrote: > Hi all, > > First of all, thanks for the 2.5.0 release! > > I have tested it in the build at my dayjob now, where we have a large > C++ application built with scons: around 7-8000 .cpp files, same > amount of headers, some code generation steps including Qt moc-ing. > Unfortunately it seems that something has happened in scons-2.5.0 that > slows down the no-op build quite significantly. This is the output of > scons --debug=time in an almost-no-op build of our source tree: > > ======================================================== > = 2.5.0 > ======================================================== > > Total build time: 933.582000 seconds > Total SConscript file execution time: 55.395000 seconds > Total SCons execution time: 858.109000 seconds > Total command execution time: 20.078000 seconds > > ======================================================== > = 2.4.1 > ======================================================== > > Total build time: 337.473000 seconds > Total SConscript file execution time: 62.303000 seconds > Total SCons execution time: 256.638000 seconds > Total command execution time: 18.532000 seconds > > ======================================================== > = 2.3.4 > ======================================================== > > Total build time: 331.774000 seconds > Total SConscript file execution time: 61.290000 seconds > Total SCons execution time: 249.606000 seconds > Total command execution time: 20.878000 seconds > > ------------------------------------------------------------ > This is with python-2.7.9 64bit on Windows 7. > > So it seems that the scons execution time has increased by a factor of > 3 in our build, between scons-2.4.1 and 2.5.0 :( > > For us the 5.5 minute no-op build time has already been an issue, so > the new 15 minute no-op build is bad news. If you have just changed a > single file, and need to build from the top to check that everything > is up to date, 15 minutes is a very long time... I'm seeing similar > slowdowns for our partial builds where we only execute some of our > SConscripts (build time going from 16 to 25 seconds for example). > > 1. Is anyone else seeing this? > 2. Any idea what changes that could cause something like this? I could > try bisecting or reverting some changes to narrow it down > 3. Is there anything else I can do, like posting the output of profiling? > > I also have some other smaller hobby C++ projects that I could profile. > > Thanks for any hints, > Thomas Berg > _______________________________________________ > Scons-dev mailing list > Scons-dev@scons.org > https://pairlist2.pair.net/mailman/listinfo/scons-dev >
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