Re: small parallel restore optimization

Andrew Dunstan <andrew@dunslane.net> writes:
> Here's a little optimization for the parallel restore code, that 
> inhibits reopening the archive file unless the worker will actually need 
> to read from the file (i.e. a data member). It seems to work OK on both 
> Linux and Windows, and I propose to apply it in a day or two.

I think you should close the file immediately at fork if you're not
going to reopen it --- otherwise it's a foot-gun waiting to fire.
IOW, not this, but something more like

	if (te->section == SECTION_DATA)
		(AH->ReopenPtr) (AH);
	else
		(AH->ClosePtr) (AH);

	... worker task ...

	if (te->section == SECTION_DATA)
		(AH->ClosePtr) (AH);

> I've seen a recent error that suggests we are clobbering memory 
> somewhere in the parallel code, as well as Olivier Prennant's reported 
> error that suggests the same thing, although I'm blessed if I can see 
> where it might be. Maybe some more eyeballs on the code would help.

Can you put together even a weakly reproducible test case?  Something
that only fails every tenth or hundredth time would still help.

			regards, tom lane