[Debian-med-packaging] Bug#1114645: does not honour the parallel tag in DEB_BUILD_OPTIONS

[Sébastien Villemot]

Source: mrtrix3
Version: 3.0.4-1
Severity: normal

Dear Maintainer,

Setting DEB_BUILD_OPTIONS="parallel=1" when building the package (for example
by passing the -j1 option to dpkg-buildpackage) does not lead to a serial
build. Instead, many g++ instances are spawn, probably as many as there are
logical cores. See Policy §4.9.1 for more details on the DEB_BUILD_OPTIONS
variable and the parallel flag.

This is a problem for building mrtrix3 on machines with a lot of logical cores
but not enough RAM for handling so many g++ processes. I personally experienced
such an out-of-memory error on a machine with 32 logical cores and 32GB RAM.

It would therefore be useful to support the selection of the number of cores
used for building the package.

Thanks for your work,

--
⢀⣴⠾⠻⢶⣦⠀  Sébastien Villemot
⣾⠁⢠⠒⠀⣿⡁  Debian Developer
⢿⡄⠘⠷⠚⠋⠀  https://sebastien.villemot.name
⠈⠳⣄⠀⠀⠀⠀  https://www.debian.org