segfaults building documentation when machine under load

[Rik]

I'm getting a vaguely repeatable situation where building the documentation
fails when the machine doing the work is under stress.

Example errors:

/bin/bash: line 1: 24234 Segmentation fault      (core dumped) /bin/bash
run-octave --norc --silent --no-history --path
/home/rik/wip/Projects_Mine/octave-dev/doc/interpreter/ --eval
"interpimages ('doc/interpreter/', 'interpft', 'txt');"
Makefile:27944: recipe for target 'doc/interpreter/interpft.txt' failed
make[2]: *** [doc/interpreter/interpft.txt] Error 139
make[2]: *** Waiting for unfinished jobs....
fatal: caught signal Segmentation fault -- stopping myself...
fatal: caught signal Segmentation fault -- stopping myself...
fatal: caught signal Segmentation fault -- stopping myself...
/bin/bash: line 1: 25316 Segmentation fault      (core dumped) /bin/bash
run-octave --norc --silent --no-history --path
/home/rik/wip/Projects_Mine/octave-dev/doc/interpreter/ --eval
"interpimages ('doc/interpreter/', 'interpderiv2', 'txt');"
Makefile:27950: recipe for target 'doc/interpreter/interpderiv2.txt' failed
make[2]: *** [doc/interpreter/interpderiv2.txt] Error 139
/bin/bash: line 1: 25338 Segmentation fault      (core dumped) /bin/bash
run-octave --norc --silent --no-history --path
/home/rik/wip/Projects_Mine/octave-dev/doc/interpreter/ --eval "plotimages
('doc/interpreter/', 'hist', 'txt');"
Makefile:27996: recipe for target 'doc/interpreter/hist.txt' failed
make[2]: *** [doc/interpreter/hist.txt] Error 139

Are other people experiencing this as well?  I think I saw something about
the Fedora buildbots also having this issue.

To be sure, I happen to have my local machine stressed.  6 of 8 cores are
pegged and then I am running 'make -j8' to do the build.  Also, uptime
reports an average load of 10.1.

A possible clue is that this usually happens when generating text files,
rather than when trying to generate actual images like png or pdf.  The
text is generated very quickly which means that race conditions might
become more apparent.  Is the script run-octave safe for parallel execution?

--Rik