Re: Using ProcSignal to get memory context stats from a running backend

Robert Haas  writes:
> On Tue, Dec 19, 2017 at 8:44 AM, Craig Ringer  wrote:
>> I didn't want to mess with the MemoryContextMethods and expose a
>> printf-wrapper style typedef in memnodes.h, so I went with a hook global.

> That looks pretty grotty to me.  I think if you want to elog/ereport
> this, you need to pass another argument to MemoryContextStats() or add
> another memory context method.  This is pretty much a textbook example
> of the wrong way to use a global variable, IMHO.

Yeah.  But please don't mess with MemoryContextStats per se ---
I dunno about you guys but "call MemoryContextStats(TopMemoryContext)"
is kinda wired into my gdb reflexes.  I think what'd make sense
is a new function "MemoryContextStatsTo(context, function_pointer)".
It's okay to redefine the APIs of the per-context-type functions
these would call, though, because nobody calls those functions directly.

			regards, tom lane