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

[Ryan Carsten Schmidt]

On Mar 7, 2025, at 04:32, Chris Jones via wrote:.
> 
> 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.

And please check Activity Monitor's Memory tab while a flang-20 build that is exhibiting this problem is underway. I checked a few build machines that are currently building flang-20 and did not see high memory use at that moment, but it might only happen at certain times during the build. If you see high memory use, attach to the ticket a screenshot from Activity Monitor or let us know about how much memory the clang processes were taking. Also make sure you're not low on disk space since that can also lead to slowness. 

And just to answer the question you asked, yes, you can tell MacPorts not to start multiple simultaneous build commands with:

sudo port install flang-20 build.jobs=1

However, to reproduce the problem to get the information from Activity Monitor, just do the build normally, letting MacPorts start many jobs.