Comment # 2 on bug 1181479 from Aaron Puchert

(In reply to Sarah Julia Kriesch from comment #0)
> https://build.opensuse.org/package/live_build_log/openSUSE:Factory:zSystems/llvm11/standard/s390x

Checked the link right now, and the latest build was successful, also the
history shows the previous build as the only failing build.

(In reply to Ruediger Oertel from comment #1)
> so a VM with 12G memory gets stuck with 6 jobs. might be a compiler bug or
> the processes really get large enough to stall the machine due to memory
> pressure.
> these are already the largest worker instances we run, so you might try with
> manually setting a different (lower) number of jobs in the specfile or
> similar.

Generally I would have gone with OOM, but 2G per job should be more than
enough. Ninja's job pools are strange, so we could have up to 5 compile jobs
plus 1 ThinLTO link job running at the same time. But even that is unlikely to
consume something remotely close to 12G.

Though a ThinLTO job being involved is likely: this is pretty late in the
build, and while the compiler itself is single-threaded, so whatever it does is
pretty well reproducible, ThinLTO jobs are multi-threaded. So it could be a
deadlock, but also a race condition if s390x has weaker memory ordering than
x86. (Which it likely has, x86 is pretty constrained.)

So there could be a bug, but unless we can observe this live there is too
little to go on I think.