RFR: 8319928: Exceptions thrown by cleanup actions passed to reinterpreted segments should be ignored

[Jorn Vernee]

On Fri, 10 Nov 2023 16:34:11 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This simplePR tweaks the factory which wraps custom cleanup actions passed to `MemorySegment::reinterpret`, so that any exception thrown by the custom cleanup is swallowed when the arena is closed.
> 
> This aligns the behavior of confined/shared session with that of implicit session (as implicit sessions are backed by a `Cleaner`, there is no way for cleanup exception to bubble up).

Not sure whether always swallowing the exceptions is the right move... it seems like an advantage that explicit arenas _can_ report exceptions thrown by cleanup actions. Silently ignoring exceptions seems bad, but something that is forced when using a Cleaner. I don't think we should extend that bad behavior to all arenas.

I do think it is problematic that we bail out of the cleanup loop on the first exception, but I suggest solving this by catching the exceptions/Throwables thrown by individual cleanup actions, and then only propagating them at the end of the cleanup loop. (where, if there are multiple exceptions we can use `addSuppressed`).

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16619#issuecomment-1807677201