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There's a decent chance checkpoint/restart has been with us since the days of paper tape. It's moderately amusing to see "save state somewhere" described as so

There's a decent chance checkpoint/restart has been with us since the days of paper tape. It's moderately amusing to see "save state somewhere" described as so new people haven't heard of it.

dunham 3y ago
I remember there was one for unix back in the 90's, I think called Condor, that could be used to migrate long running processes to other machines. (I think the tricky part was restoring external connections like file handles.) And before that, there were TeX and emacs, which do a memory dump and restore to save time loading their initial state. One of those, I think emacs, would tweak a core dump file to be a valid executable again.
Spivak 3y ago
Checkpoint/Restore I feel is a bigger concept than just saving state. At the zeroth level it's a system that can correctly stop and serialize a running process (as criu https://github.com/checkpoint-restore/criu https://github.com/checkpoint-restore/criu has shown is a huge pain in the ass to still not be perfect) in a way that can initiated from within the process itself. The 1st level more-work-but-easier way to do this is to build or use a heavily constrained VM/language you run from within your main application that doesn't allow for most of the hard problems to even exist. I can't find any ready-made tools to do this that I wouldn't consider an endeavor. Emacs has to be the most famous application to utilize dump/restore state but it's not exactly turnkey.
JohnFen 3y ago
I've been in the industry for so long now as to see this pattern repeat often enough that I've come to accept it as a sort of universal truth: nearly everything that people think is "new" is actually an echo and (hopefully) refinement of something that has come before. I am hard-pressed to think of anything in the software world today that is actually, truly, new. We all stand on the shoulders of giants.
yencabulator 3y ago
The challenge is purely in how to make it perform well. Dumping the whole memory was a lot more viable when that was only a few kilobytes.

There's a decent chance checkpoint/restart has been with us since the days of paper tape. It's moderately amusing to see "save state somewhere" described as so new people haven't heard of it.

dunham 3y ago

I remember there was one for unix back in the 90's, I think called Condor, that could be used to migrate long running processes to other machines. (I think the tricky part was restoring external connections like file handles.) And before that, there were TeX and emacs, which do a memory dump and restore to save time loading their initial state. One of those, I think emacs, would tweak a core dump file to be a valid executable again.

Spivak 3y ago

Checkpoint/Restore I feel is a bigger concept than just saving state. At the zeroth level it's a system that can correctly stop and serialize a running process (as criu https://github.com/checkpoint-restore/criu https://github.com/checkpoint-restore/criu has shown is a huge pain in the ass to still not be perfect) in a way that can initiated from within the process itself. The 1st level more-work-but-easier way to do this is to build or use a heavily constrained VM/language you run from within your main application that doesn't allow for most of the hard problems to even exist. I can't find any ready-made tools to do this that I wouldn't consider an endeavor. Emacs has to be the most famous application to utilize dump/restore state but it's not exactly turnkey.

JohnFen 3y ago

I've been in the industry for so long now as to see this pattern repeat often enough that I've come to accept it as a sort of universal truth: nearly everything that people think is "new" is actually an echo and (hopefully) refinement of something that has come before. I am hard-pressed to think of anything in the software world today that is actually, truly, new. We all stand on the shoulders of giants.

yencabulator 3y ago

The challenge is purely in how to make it perform well. Dumping the whole memory was a lot more viable when that was only a few kilobytes.