gen-transform: Cannot fork (Resource temporarily unavailable)

[Thomas Klausner <tk%giga.or.at@localhost>]

Hi!

In my bulk builds on tmpfs, NetBSD-current/amd64, quite regularly
(nearly every bulk build, but different packages each time) I see
build failures where the log looks like this:

===> Creating toolchain wrappers for pango-1.36.0nb1
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
/scratch/devel/pango/work/.wrapper/tmp/gen-transform: Cannot fork (Resource 
temporarily unavailable)
...

Repeating the build of the same package usually works. (I don't
remember having needed more than a second try.)

I have MAKE_JOBS=8 in my /etc/mk.conf, but I'm not sure that even
affects this step.

Anyone else seen this?
Does anyone have ideas what could cause this?
 Thomas