Re: Shortcoming in CLOBBER_FREED_MEMORY coverage: disk buffer pointers

Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> writes:
> On 1/26/15 6:11 PM, Greg Stark wrote:
>> Fwiw I think our experience is that bugs where buffers are unpinned get exposed pretty quickly in production. I suppose the same might not be true for rarely called codepaths or in cases where the buffers are usually already pinned.

> Yeah, that's what I was thinking. If there's some easy way to correctly associate pins with specific code paths (owners?) then maybe it's worth doing so; but I don't think it's worth much effort.

If you have a working set larger than shared_buffers, then yeah it's
likely that reference-after-unpin bugs would manifest pretty quickly.
This does not necessarily translate into something reproducible or
debuggable, however; and besides that you'd really rather that such
bugs not get into the field in the first place.

The point of my Valgrind proposal was to provide a mechanism that would
have a chance of catching such bugs in a *development* context, and
provide some hint of where in the codebase the fault is, too.

regards, tom lane