[CRIU] CRIU with GNU Screen: dumping and restoring entire process trees under Screen

[Pavel Tikhomirov]

Hello Nikhil!

I'm not sure anyone actually checked that criu works on wsl, some
kernel interfaces may be not implemented.

I've just tried criu on WSL and got some errors:


:/home/snorch/devel/criu# criu check
Warn  (criu/kerndat.c:659): Can't load /run/criu.kdat
Error (criu/util.c:714): exited, status=3
Error (criu/util.c:714): exited, status=3
Error (criu/kerndat.c:47): Can't open 0/pagemap on procfs: No such
file or directory
Error (criu/sysctl.c:368): Can't open sysctl vm/mmap_min_addr: No such
file or directory
Warn  (criu/kerndat.c:137): Can't fetch vm/mmap_min_addr value, use
default 0x10000
:/home/snorch/devel/criu#

Best Regards, Tikhomirov Pavel.

пт, 17 апр. 2020 г. в 13:06, Nikhil Nair <nnair at pobox.com>:
>
> Hi,
>
> I'm completely new to CRIU, and it sounds very interesting.
>
> On the website, I found a page about using CRIU to dump and restore entire
> process trees under screen, but it seems the page is empty, and has been so
> for 3 years.
>
> I'm hopeful, though, that the existence of that page means this is very
> doable indeed.  Is that right?  I've searched the archive of this list for
> an answer to this, as well as Googling it, but couldn't find anything.
>
> Ideally, I'd like to be able to have a script running in the background
> which will take a snapshot of my screen session (which typically has one
> Emacs session running within it, plus a number of bash shells with
> different CWDs and screen contents) every several minutes (and then delete
> old snapshots so that it only keeps the last few at any time).  I presume
> taking a snapshot will involve both a CRIU dump and taking a copy of my
> relevant working directories.
>
> The reason I'm looking at this is that I'm shifting to develop on Windows
> 10 using their Windows Subsystem for Linux (WSL), running Ubuntu.  It's
> pretty much binary compatible with Ubuntu running on a normal AMD64
> platform with a text console (I'm not using X).
>
> The issue is that, sometimes, the host Windows machine reboots, without
> always asking my permission - or, at least, only waiting so long, so if I'm
> away from the machine, I could come back to find the machine rebooted, and
> my screen session lost.  There are things I can do to make reboots less
> likely, but I don't trust Windows not to reboot if it considers it
> important, without giving me a chance to save my work.
>
> But honestly, even if I did have a chance to save my work, taking a
> snapshot would be much easier than setting up the screen session from
> scratch, anyway.
>
> So... what's the situation?  Is this reasonably straightforward?
>
> If the above won't work, I could look into using lxc under WSL, and
> snapshot the container; but that seems overkill, for what I'm after.
> Docker would have been an option, but I gather (from the CRIU website) that
> dumping an interactive container isn't yet enabled in Docker.
>
> Cheers,
>
> Nikhil.
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