Of the choices the java-style hibernate is what we do. For example if we have a long sequence we do every run we will run that sequence once, save and then use the snapshot to get to the "good/interesting" verification faster.

Target platform is Linux so your last point goes away :-(

Just to clarify (with only a few minutes of reading...much more to do), your thought is to use the Streamer module to stream the run of the thread as it goes, then when we do a restore() grab the previous state...Interesting.
Again, much more to read, but is there a defstash for the top level thread, or are Perl threads not done that way?

Off to read some! Thanks!