Catching core files in read-only jails

[J David]

If an application is running on a production server in a read-only
jail for security purposes, and it crashes occasionally due to some
unknown bug, is there any way to catch a core file?

Setting kern.corefile seems to still be relative to the jail.  (Or, at
least, no corefile is generated.)

There are a lot of these processes and they don’t crash very often, so
leaving gdb attached isn’t really feasible either.  (It’s been tried,
but apparently requires a bit more luck than is currently in
evidence.)

Thusfar all attempts to get it to crash in a controlled/test
environment have also been unsuccessful.

Does anyone have any ideas for how to find out what’s causing the crash?

Thanks for any advice!