I've just forced a core dump of a misbehaving multithreaded program and am looking at it using gdb to good effect.

Can Lazarus be used as a post-mortem debugger, reminiscent of products from Logitech et al?

probably not without changes.

I havent used gdb for this either, so I am not aware which commands you can send to gdb.

I guess that the code used for "attach" can be copied/modified to load a core dump.

then you might be able do use the stack, and watches. but I do not know

In this case all I did was (before running program) ulimit -Hc unlimited followed by (while looking at stuck program) gcore <pid> and then gdb <binary> core.<pid> after which I could use bt etc. In principle, something similar should work for a program which had failed with a bus error or segment violation.

I'm converting somebody else's code from single- to multithreaded. If run in the context of Lazarus's own debugging it's fine, but if running "unattended" it locks up with a race condition about 75% of the time. So being able to look at a snapshot is really extremely useful, even if I can't take full control.