BUG #14936: Huge backend memory usage during schema dump of database with many views

The following bug has been logged on the website:

Bug reference: 14936
Logged by: Maksym Boguk
Email address: maxim(dot)boguk(at)gmail(dot)com
PostgreSQL version: 9.5.10
Operating system: Linux
Description:

Hi,

I got off-list report of the following issue:
server used all memory and crash with OOM during pg_dump of the database
with many schemes and views.

After removing all extra stuff problem can be show with simple run the
following query on the database:
select (CASE WHEN pg_has_role(c.relowner, 'USAGE'::text) THEN
pg_get_viewdef(c.oid) ELSE NULL::text END) as view_src from pg_class c where
(c.relkind = 'v'::"char");

This query used up to 15GB backend local memory before finishing in one
hour.

The database contains 22 schema with ~1000views in each schema, average view
length ~2kb (3+ table in each view), so total ~20-25k views.

If required, I can ask for dump of the few schemes to provide self-contained
test case.

Memory leak somewhere inside pg_get_viewdef?

Kind Regards,
Maksym