Re: Query on pg_stat_activity table got stuck

neeraj kumar <neeru(dot)cse(at)gmail(dot)com> writes:
> We got more information about this issue. There is one backend process
> still present into beentry which has changecount as odd value. However this
> process is long gone/terminated. It means when this process was
> killed/terminated its entry was not cleaned from beentry list. There seems
> to be some shutdown hook which cleans beentry if process is
> killed/terminated that somehow was not kicked off ?

No, that's the point: there isn't any such cleanup code. The design
idea here was that we'd only have short straight-line code segments
with no possible way to throw an error while changecount is odd.
Then somebody abused the heck out of that ...

regards, tom lane