[Scons-dev] Excessive exec calls at startup

[William Blevins]

On second thought, I should provide some documentation as a citation which
is for some reason eluding me, so I may or may not be crazy.

On Tue, Nov 24, 2015 at 12:54 AM, William Blevins <wblevins001 at gmail.com>
wrote:

>
>
> On Mon, Nov 23, 2015 at 9:50 PM, Johan Holmberg <johan556 at gmail.com>
> wrote:
>
>> On Mon, Nov 23, 2015 at 11:18 AM, Ivan Nedrehagen <ivan at nedrehagen.com>
>> wrote:
>>
>>> Just an idea, as creating loads of new environments aren't unusual.
>>> Perhaps caching the version like this would be impossible, but how about
>>> caching results based on executable paths and arguments?
>>> Regards,
>>> Ivan Nedrehagen
>>>
>>>
>>
>> I think that was what my patch tried to do. If the parameter named "cc"
>> had the value "gcc", the call to env.WhereIs(cc) returned "/usr/bin/gcc",
>> and I used that full path as key in the dict caching the results. I just
>> assumed that "/usr/bin/gcc --version" would return the same thing each time
>> it was called. (perhaps WhereIs() is not the right way to find the absolute
>> path of a program, but it seemed to work).
>>
>>
>> On Mon, Nov 23, 2015 at 5:04 AM, Jason Kenny <dragon512 at live.com> wrote:
>>
>>> I make a new environments myself all the time. The trick is to Clone() a
>>> new environment, not create a new one from scratch each time you need a new
>>> one.
>>> Jason
>>>
>>
>>
>> I hadn't realised that Clone() was much cheaper. I tried just now with
>> Clone() and it works well for me, and is even slightly faster than my patch.
>>
>
> Clone creates a substitute environment from the original rather than
> creating a branch new environment, so if you are only overriding a few
> variables, then Clone is much cheaper memory and performance wise.
>
>
>>
>> /Johan Holmberg
>>
>>
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>>
>>
>
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