DO with a large amount of statements get stuck with high memory consumption

I've noticed that pl/pgsql functions/do commands do not behave well
when the statement resolves and frees memory.   To be clear:

FOR i in 1..1000000
LOOP INSERT INTO foo VALUES (i);
END LOOP;

...runs just fine while

BEGIN INSERT INTO foo VALUES (1); INSERT INTO foo VALUES (2); ... INSERT INTO foo VALUES (1000000);
END;

(for the curious, create a script yourself via
copy ( select   'do $$begin create temp table foo(i int);' union all select   format('insert into foo values (%s);', i)
fromgenerate_series(1,1000000) i union all select 'raise notice ''abandon all hope!''; end; $$;'
 
) to '/tmp/breakit.sql';

...while consume amounts of resident memory proportional to the number
of statemnts and eventually crash the server.  The problem is obvious;
each statement causes a plan to get created and the server gets stuck
in a loop where SPI_freeplan() is called repeatedly.  Everything is
working as designed I guess, but when this happens it's really
unpleasant: the query is uncancellable and unterminatable, nicht gut.
A pg_ctl kill ABRT <pid> will do the trick but I was quite astonished
to see linux take a few minutes to clean up the mess (!) on a somewhat
pokey virtualized server with lots of memory.  With even as little as
ten thousand statements the cleanup time far exceed the runtime of the
statement block.

I guess the key takeaway here is, "don't do that"; pl/pgsql
aggressively generates plans and turns out to be a poor choice for
bulk loading because of all the plan caching.   Having said that, I
can't help but wonder if there should be a (perhaps user configurable)
limit to the amount of SPI plans a single function call should be able
to acquire on the basis you are going to smack into very poor
behaviors in the memory subsystem.

Stepping back, I can't help but wonder what the value of all the plan
caching going on is at all for statement blocks.  Loops might comprise
a notable exception, noted.  I'd humbly submit though that (relative
to functions) it's much more likely to want to do something like
insert a lot of statements and a impossible to utilize any cached
plans.

This is not an academic gripe -- I just exploded production :-D.

merlin