On Fri, Dec 21, 2018 at 04:24:20PM -0500, Andrew Dunstan wrote:
> On 12/21/18 4:04 PM, Thomas Munro wrote:
> > On Sat, Dec 22, 2018 at 7:32 AM David Fetter <david@fetter.org> wrote:
> >> On Sat, Dec 22, 2018 at 07:03:32AM +1100, Thomas Munro wrote:
> >>> That talks about using -D__ANDROID_API__=23 (or presumably higher) to
> >>> make sure that sigtimedwait is exposed by signal.h. Something similar
> >>> may be afoot here.
> >> That worked perfectly...to expose the next issue, namely that at least
> >> part of the System-V IPC mechanisms have been left out. Do we support
> >> other systems where this is true?
> > Interesting, they left that stuff out deliberately out basically
> > because it all sucks:
> >
> >
https://android.googlesource.com/platform/ndk/+/4e159d95ebf23b5f72bb707b0cb1518ef96b3d03/docs/system/libc/SYSV-IPC.TXT
> >
> > PostgreSQL currently needs SysV shm just for the small segment that's
> > used for preventing multiple copies running in the same pgdata. You'd
> > need to find a new way to do that. We don't use SysV semaphores
> > (though we can) or message queues.
>
> That doc says:
>
> Killing processes automatically to make room for new ones is an
> important part of Android's application lifecycle implementation.
>
> How's that going to play with Postgres? Sounds like the OOM killer on
> steroids.
I don't know precisely how it's going to play with Postgres, but
Termux does supply a Postgres in its native packages. That package
appears to work, at least in the single-connection case, so they're
doing something somehow to get it up and running.
It could be that Android won't be a platform we recommend for high
workloads, at least as long as these things remain true.
Best,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778
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