RFR: 8251850: Simplify ResourceMark constructors using delegation

[Thomas Stüfe]

On Tue, Aug 18, 2020 at 9:52 AM Kim Barrett <kim.barrett at oracle.com> wrote:

> > On Aug 17, 2020, at 10:44 PM, David Holmes <david.holmes at oracle.com>
> wrote:
> >
> > Hi Kim,
> >
> > Not a full review - sorry. Have you tested what happens if a resource
> leak is introduced? The _warned variable was used, IIUC, to avoid hitting
> recursive errors during error reporting.
>
> OH!  The recursive case hadn’t occurred to me!
>
> Poorly named and poorly commented variable from before the beginning of
> the mercurial age,
> so hard to track down the changeset that introduced it to see if that shed
> some light.  Good
> thing we have some institutional memory :)
>
> I will do something about that, and then try to figure out how to trigger
> it.
>

You could rig up something using -XX:ErrorHandlerTest
(VMError::controlled_crash) and allocate from the same ResourceArea again
inside the error handler. There are tests for similar things, e.g.
SafeFetch, see hotspot/jtreg/runtime/ErrorReporting.

But I am not sure this is worthwhile. IMHO it would be better to fix the
places where ResourceAreas are used in error reporting instead of muting
this warning for recursive calls. Because ideally we do not want
allocations to happen at all during error reporting.

BTW at SAP we have generic tests which scan hs-err files for secondary
errors, but they are high maintenance.

Cheers, Thomas