Re: shall we have a TRACE_MEMORY mode

On 6/20/06, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> One idea that comes to mind is to have a compile time option to record
> the palloc __FILE__ and _LINE__ in every AllocChunk header. Then it
> would not be so hard to identify the culprit while trawling through
> memory. The overhead costs would be so high that you'd never turn it on
> by default though :-(

Will adding 8 bytes, that too as a compile-time option, be a big
overhead? 4 for __FILE__'s char* and 4 for __LINE__'s int; this,
assuming 32 bit arch, and that no duplicates of __FILE__ string for
each file are stored in the binary by the compiler, also called
'Enable string Pooling' in VS.Net
(http://msdn2.microsoft.com/en-us/library/s0s0asdt.aspx)

> Another thing to consider is that the proximate location of the palloc
> is frequently *not* very useful. For instance, if your memory is
> getting eaten by lists, all the palloc traces will point at
> new_tail_cell(). Not much help. I don't know what to do about that
> ... any ideas?

We can consider such utility functions equivalent to palloc, hence the
caller's __FILE__ and __LINE__ will passed in to these functions, and
these functions will use the same to call the palloc (or the palloc's
#define expanded). So, in effect, in the log files, allocation will
seem to have been done from the location which called the utility
function.

Regards,
Gurjeet.