Re: JIT causes core dump during error recovery

I wrote:
> What I think is the right solution is to fix things so that
> seemingly-no-longer-used jit compilations are not thrown away
> until transaction cleanup.  I don't know the JIT code nearly
> well enough to take point on fixing it like that, though.

Or maybe not.  I found by bisecting that it doesn't fail before
2e517818f (Fix SPI's handling of errors during transaction commit).
A salient part of that commit message:

    Having made that API redefinition, we can fix this mess by having
    SPI_commit[_and_chain] trap errors and start a new, clean transaction
    before re-throwing the error.  Likewise for SPI_rollback[_and_chain].

So delaying removal of the jit-created code segment until transaction
cleanup wouldn't be enough to prevent this crash, if I'm reading
things right.  The extra-pstrdup solution may be the only viable one.

I could use confirmation from someone who knows the JIT code about
when jit-created code is unloaded.  It also remains very unclear
why there is no crash if we don't force both jit_optimize_above_cost
and jit_inline_above_cost to small values.

            regards, tom lane