Re: buildfarm: strange OOM failures on markhor (running CLOBBER_CACHE_RECURSIVELY)

Hi,

On 2014-05-17 22:33:31 +0200, Tomas Vondra wrote:
> Anyway, the main difference between the analyze snapshot seems to be this:
>
> init: CacheMemoryContext: 67100672 total in 17 blocks; ...
> 350MB: CacheMemoryContext: 134209536 total in 25 blocks; ...
> 400MB: CacheMemoryContext: 192929792 total in 32 blocks; ...
> 500MB: CacheMemoryContext: 293593088 total in 44 blocks; ...
> 600MB: CacheMemoryContext: 411033600 total in 58 blocks; ...

Hm, so something is definitely leaking memory inside CacheMemoryContext
itself. Is that happening constantly or just with individual tests?

> Not sure if there's something wrong with the SELECT memory context. It
> has ~1500 of nested nodes like these:
>
> SQL function data: 24576 total in 2 blocks; ...
> ExecutorState: 24576 total in 2 blocks; ...
> SQL function data: 24576 total in 2 blocks; ...
> ExprContext: 8192 total in 1 blocks; ...
>
> But maybe it's expected / OK.

I'd guess that's a recursive function call. Any chance you know what's
been executing at that point? I'd bet it's been the 'errors' check. That
has:
-- Check that stack depth detection mechanism works and
-- max_stack_depth is not set too high
create function infinite_recurse() returns int as
'select infinite_recurse()' language sql;
\set VERBOSITY terse
select infinite_recurse();
ERROR: stack depth limit exceeded

which'd pretty much produce a tree of executions like yours.

Greetings,

Andres Freund