Re: Deadlock between concurrent index builds on different tables

Jeremy Finzel wrote:
> On Tue, Dec 26, 2017 at 10:28 AM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
> wrote:
>
> > Jeremy Finzel wrote:
> > > >
> > > >> Each index build needs to wait for all other transactions
> > > >> (Including the ones used by the other index build) to finish.
> > > >> So I don't think a deadlock here is unexpected.
> >
> > > Does that mean I should never build more than one concurrent index at
> > > a time within the entire cluster? If so, that is not clear from the
> > > documentation.
> >
> > No, there is no such expectation. Jeff analyzed your scenario,
> > discovered a bug and sent a patch to fix it -- care to test it and
> > report back? You can get it from here:
> >
> > https://www.postgresql.org/message-id/CAMkU=1ztk3TpQdcUNbxq93pc80FrXUjpDWL
> > GMeVBDx71GHNwZQ(at)mail(dot)gmail(dot)com

> I would be thrilled to review it, but I need a little direction as I have
> not done a patch review before. I have been reading through some of the
> developer FAQ and patch info. The attached file is simply a git diff, so
> I'm not sure how I am to use this? Is there a specific source version I
> can download and compile? I know where to get the current master, etc.,
> from git, but where can I get the patched version or what is the proper way
> to apply the patch to current master?

I don't think a patch review as such is necessary -- that code is very
complex and you'd need to learn about a lot of internals (though I won't
stop if you want to learn). I was thinking about testing it, instead.

To create a patched build,
1. get a clone with the branch you're on. Assuming you're on 9.6, it'd
be like this
git clone <URL> -b REL9_6_STABLE

2. apply the patch on top
cd postgresql
patch -p1 < /path/to/file.diff
# you could use "git apply" instead (or "git am", but not with this one)

3. configure and make
./configure <configure options>
make
make install

4. run it
initdb -D <somedir> # to create a fresh datadir
pg_ctl <whatever>

You may need additional packages (zlib devel, readline devel, others;
see https://www.postgresql.org/docs/9.6/static/installation.html)

For the options in step 3 you could use whatever your current server
has; use "pg_config --configure" to find these out. You're gonna need
same flags if you want to use your existing data directory.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services