[Scons-dev] Subst() replacement?

[Bill Deegan]

Jason,

The code I have is still a work in progress.
Putting it in parts first doesn't make sense to me as when it's ready I'll
be dropping it into SCons itself, though likely as a switchable alternative
initially.

I'll be back to working on it in about a month I expect. Maybe sooner.

-Bill

On Mon, Feb 18, 2019 at 11:18 AM Jason Kenny <dragon512 at live.com> wrote:

> Hi Bill,
>
> I know in the past we have talked about various things to do to fix up
> Scons. One of the items was the subst engine we have. Currently for me the
> issue with Parts is that I use the Subst engine to pass data around between
> different components in a automated way. This works well minus two issues:
>
> 1) it can take time. However I have various tweaks in the object I pass to
> the subst call to help cache a number of cases.
> 2) stack depth. This is the major issue for me at the moment.
>
> The issue with with 2) is seen with -j based builds which can lead to seg
> faults. Depending on the build, it is common to have some depth of 10-20+
> components. This can lead to a stack of depth per thread of 250 to 300+.
> When doing a -j based build this blows the stack in a bad way.
>
> one can easily get stack with this pattern:
>
> ...
> File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 543, in substitute
>     return self.expand(args, lvars)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 495, in expand
>     return list(map(func, s))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 494, in func
>     return conv(substitute(l, lvars))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 526, in substitute
>     result = _dollar_exps.sub(sub_match, args)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 525, in sub_match
>     return self.conv(self.expand(match.group(1), lvars))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 491, in expand
>     return self.substitute(s, lv)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 543, in substitute
>     return self.expand(args, lvars)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 509, in expand
>     return self.substitute(s, lvars)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 543, in substitute
>     return self.expand(args, lvars)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 495, in expand
>     return list(map(func, s))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 494, in func
>     return conv(substitute(l, lvars))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 543, in substitute
>     return self.expand(args, lvars)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 495, in expand
>     return list(map(func, s))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 494, in func
>     return conv(substitute(l, lvars))
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 526, in substitute
>     result = _dollar_exps.sub(sub_match, args)
>   File "/build-env/lib/python3.6/site-packages/scons/SCons/Subst.py", line
> 525, in sub_match
> ...
>
> I had mentioned in the past I want to not use the subst call as much, but
> change this with something else is non trivial at the moment. I do recall
> you had done some work on this. I am looking at trying to fix the subst
> logic in Scons . What I propose to do it to override the subst module in
> SCons with Parts. The goal would to be to show a better version we could
> the move in to Scons with minimum effort as well as allow me to move
> forward with out having to block on a new SCons drop.
>
> I believe you had done work on this already. I was hoping I could try to
> start with that with hope this can be used to reduce the recursion issues
> in SCons. This seemed to be better than start from scratch.
>
> Oh course if you have a better idea I am
>
> Jason
>
>
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