[Scons-users] Performance of version 2.5.0 vs 2.3.0 on Windows host dropped significantly

[Vasily]

Hi,

You might also do some profiling of fast and slow cases and compare the
results to see if there is any hint on what's slowing down your build.

Thanks,
Vasily
08 авг. 2016 г. 10:17 пользователь "Dirk Bächle" <tshortik at gmx.de> написал:

> Hi Henrik,
>
> On 08.08.2016 03:23, hmnews at proconx.com wrote:
>
>> Hi all,
>>
>> We just updated to Scons 2.5.0 after using happily 2.3.0 for years.
>>
>> Sadly we found performance to have dropped significantly and I wonder
>> what the contributing factor could be.
>>
>> Platform: Windows 10
>> Python: 2.7.12 64-bit
>>
>>
> some more questions about this: Can you compare the times for a build
> under Linux as well, or do you build under Windows only?
>
> [...]
>>
>> However with 2.5.0 execution time blows out to 11.8s, more than 4 times
>> longer!!!
>>
>>
> You say that this is a benchmark project. What happens to the "real"
> projects? Do they scale, i.e. do they also take about 4 times longer each?
>
> [...]
>>
>> I appears that Scons takes much longer in 2.5.0 to analyse the build
>> targets. This is also apparent when running scons-2.5.0 --debug=prepare
>> which takes noticeable longer to to print the file list.
>>
>> I also compared the dependency tree for both version using --debug=tree
>> and they are identical.
>>
>>
> Good to know, because we have changed "scanning" in a few places, which
> could've explained the longer times too.
>
> Has anybody experienced a similar behaviour and is there any tuning
>> parameter to make 2.5.0 offer the same performance of 2.3.0?
>>
>
> If there were such a parameter, it would definitely be "on" by default. ;)
>
>
>> Is there any debug option to analyse why Scons 2.5.0 takes such a long
>> execution time?
>>
>
> In general, SCons uses most of its time during a "zero build" (nothing to
> do), "subst"ing variable values. If you're prepared for a long and
> technical read have a look at https://bitbucket.org/scons/sc
> ons/wiki/WhySconsIsNotSlow . You might also want to check out the
> "fastcpp" tool at https://bitbucket.org/dirkbaechle/scons_fastcpp to get
> an idea of how to "tweak" your environment/toolchain to get more speed in
> general.
>
> I hope these first comments already help you a little further.
>
> Best regards,
>
> Dirk
>
>
>
>> Thanks
>>
>> Henrik
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