I wrote:
> ReorderBuffer: 223302560 total in 26995 blocks; 7056 free (3 chunks); 223295504 used
> The test case is only inserting 50K fairly-short rows, so this seems
> like an unreasonable amount of memory to be consuming for that; and
> even if you think it's reasonable, it clearly isn't going to scale
> to large production transactions.
> Now, the good news is that v11 and later get through
> 006_logical_decoding.pl just fine under the same restriction.
> So we did something in v11 to fix this excessive memory consumption.
> However, unless we're willing to back-port whatever that was, this
> test case is clearly consuming excessive resources for the v10 branch.
I dug around a little in the git history for backend/replication/logical/,
and while I find several commit messages mentioning memory leaks and
faulty spill logic, they all claim to have been back-patched as far
as 9.4.
It seems reasonably likely to me that this result is telling us about
an actual bug, ie, faulty back-patching of one or more of those fixes
into v10 and perhaps earlier branches.
I don't know this code well enough to take point on looking for the
problem, though.
regards, tom lane