flang-20 port is building VERY SLOWLY, "memory pressure" (Activity monitor) is very high

[Kenneth Wolcott]

Hi Chris;

  I'm sorry that I did not capture any details for this issue.  What I
remember is that there where several "STUCK" clang entries shown in top.
The build step count (not sure what it is formally called; the number that
increments inside square brackets) would take about ten to twenty minutes
to increment (I guess that is the equivalent of single-threaded in a very
low RAM environment!).

  Should this problem occur again, what output should I gather and what
tools do I need to obtain such output? memstat? vmstat?

Thanks,
Ken Wolcott

On Fri, Mar 7, 2025 at 2:31 AM Chris Jones via macports-users <
macports-users at lists.macports.org> wrote:

>
>
> On 07/03/2025 3:39 am, Joshua Root wrote:
> >> Building flang has always been CPU+RAM intensive, but it looks like it
> is
> >> thrashing now.
> >>
> >>    Is there a way to make it go single threaded?  I have like ten
> "stuck"
> >> clang processes...
> >
> > A better solution would be to set build.mem_per_job to something higher
> > in the port. It defaults to 1024 (MB) and is used to limit the number of
> > parallel build processes based on the available memory.
>
> 1GB per thread is from what I have seen not unreasonable for flang. I've
> never seen any specific issues myself so would like to see more details
> of the problem seen before changing anything here.
>
> Kenneth please open a trac ticket with more details, how many thread are
> start for you, where in the build specifically do you have issues etc.
>
> Chris
>
>
>
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