Add support for a PIO_RUN_NR_OF_CORES env variable and/or platformio.ini setting

[Bascy]

I would love to run build with one less core than all to maintain a responsive computer while building, but the default behavior of p;io run is to use all cores avaible.

It would be really nice if we could specify the number of cores to use with and evn varibale or platformio.ini setting

[ivankravets]

Please re-test with pio upgrade --dev.

[Bascy]

Can i also set this in the platformio.ini?

[ivankravets]

I'm sorry, no. This feature is mentioned for the first time in the last ten years. I don't think there is a sense of complicating platformio.ini.