Re: scorpionfly needs more semaphores

Thus said Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> on Wed, 18 Sep 2019 00:33:19 -0400
> Thomas Munro <thomas(dot)munro(at)gmail(dot)com> writes:
>> We're seeing occasional failures like this:
>> running bootstrap script ... 2019-09-13 12:11:26.882 PDT [64926]
>> FATAL: could not create semaphores: No space left on device
>> 2019-09-13 12:11:26.882 PDT [64926] DETAIL: Failed system call was
>> semget(5728001, 17, 03600).
>
>> I think you should switch to using "named" POSIX semaphores by
>> building with USE_NAMED_POSIX_SEMAPHORES (then it'll create a
>> squillion little files under /tmp and mmap() them), or increase the
>> number of SysV semaphores you can create with sysctl[1], or finish
>> writing your operating system[2] so you can switch to "unnamed" POSIX
>> semaphores :-)
>
> I'd recommend the second option. Since the discussion in [1],
> we've fixed our docs for OpenBSD to say
>
> In OpenBSD 3.3 and later, IPC parameters can be adjusted using sysctl,
> for example:
> # sysctl kern.seminfo.semmni=100
> To make these settings persist over reboots, modify /etc/sysctl.conf.
> You will usually want to increase kern.seminfo.semmni and
> kern.seminfo.semmns, as OpenBSD's default settings for these are
> uncomfortably small.

Thanks, Thomas and Tom for reaching out to me. I certainly don't want to
recompile my kernel, as I basically run -current OpenBSD via snapshots.

That said, I've made the adjustment to the sysctl:

$ sysctl | ag kern.seminfo.semmni
kern.seminfo.semmni=100

>
> Scorpionfly also seems to be having problems with its git repo breaking on
> a regular basis. I have no idea what's up with that.

That is a mystery to me as well. 9.4 stable seems to be the branch with
the most problems:
https://buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=scorpionfly&br=REL9_4_STABLE

My cronjobs:
0 */6 * * * cd /home/pgbuilder/bin/REL10 && ./run_build.pl --verbose
0 */12 * * * cd /home/pgbuilder/bin/REL10 && ./run_branches.pl --run-all

I'm willing to make more tweaks to prevent these false positives, so
feel free to continue monitoring to see how things work out over the
next several builds.

>
> regards, tom lane
>