Re: "multiple backends attempting to wait for pincount 1"

Andres Freund <andres@2ndquadrant.com> wrote:

> How did you get to that recipe?

I have been working on some patches to allow vacuum to function in
the face of long-held snapshots.  (I'm struggling to get them into
presentable shape for the upcoming CF.)  I was devising the most
diabolical cases I could to try to break my patched code and
started seeing this error.  I was panicked that I had introduced
the bug, but on comparing to the master branch I found I was able
to cause it there, too.  So I saw this a couple days before the
report on list, and had some cases that *sometimes* caused the
error.  I tweaked until it seemed to be pretty reliable, and then
used that for the bisect.

I still consider you to be the uncontested champion of diabolical 
test cases, but I'm happy to have hit upon one that was useful 
here.  ;-)

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company