Hi Kapil, Thank you for your insights. You are spot on. The /proc/<PID>/maps of the processes I try to serialise with DMTCP contain the exact list of incorrect filepaths that DMTCP spits out.
Making checkpoints does generate non-empty *.dmtcp files together with the restart scripts, but running dmtcp_restart_script.sh coredumps with the following (expected) last words: [30211] mtcp_restart_nolibc.c:1053 fix_filename_if_new_cwd: error 13 creating directory /var/lib/lxc in path of /var/lib/lxc/rootfs/usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache Segmentation fault (core dumped) I do not know the answers to your other questions about LXC and path translation. Thanks again for your help, Alexandre On Sat, Oct 5, 2013 at 10:51 PM, Kapil Arya <ka...@ccs.neu.edu> wrote: > Hi Alexandre, > > Thanks for contacting us about this issue. > > We haven't tried DMTCP with LXC earlier so we can't be sure about the > situation. However, I guess you are seeing these warnings because > /proc/self/maps is listing those files with absolute paths. Can you verify > this by looking at /proc/self/maps of a process running inside the > container? > > In any case, was DMTCP able to generate checkpoint images? Also, what is a > good way to figure out whether a process is running inside a container? > Also, is there a way to translate between absolute and _fake_ paths? > > We might need to write a small DMTCP plugin for LXC to takes care of this. > > Kapil > > > On Sat, Oct 5, 2013 at 4:31 PM, Alexandre Gravier <al.grav...@gmail.com> > wrote: >> >> Hello, >> >> I'm trying to use DMTCP to save my user sessions on an online service >> that offers LXC virtual machines. The service shutdowns the container >> after 15 minutes of inactivity on my side, and I would like to be able >> to save my tmux session and all related processes to disk before that >> happens. >> >> So, I've compiled DMTCP 2.0, and 40 out of 45 tests pass*. I figured >> that I may try to do something simple first, so I launch the >> coordinator in a terminal, and `bin/dmtcp_launch cat` in another. The >> coordinator notes that "NOTE at dmtcp_coordinator.cpp:1039 in >> onConnect; REASON='worker connected'". It all seems fine, and the >> clients list contains my cat. >> >> The problem comes when I actually make a checkpoint using 'c' in the >> coordinator. The coordinator goes through what seems to be a >> reasonable list of stages, from "starting checkpoint, suspending all >> nodes" to "restarting all nodes", but in the terminal where the >> dmtcp-monitored "cat" is running, there is an avalanche of errors that >> all look like: >> >> [11795] mtcp_writeckpt.c:718 write_ckpt_to_file: >> ERROR: error statting >> >> /var/lib/lxc/vm-524f2a6f88716f1d3800785a/overlay/home/agravier/dmtcp-2.0/plugin/ipc/libdmtcp_ipc.so >> : No such file or directory >> [11795] mtcp_writeckpt.c:718 write_ckpt_to_file: >> ERROR: error statting >> /var/lib/lxc/rootfs/lib/x86_64-linux-gnu/ld-2.17.so : No such file or >> directory >> >> And there are dozens of those. >> >> Visibly, mtcp is looking for files using their absolute path *outside* >> of the LXC container, which, of course, does not correspond to their >> paths inside of it. >> >> I would like to understand how LXC chroots in a way that still allows >> MTCP to get hold of the original filepaths. Why does MTCP get confused >> when other applications don't? Or rather, why it doesn't get confused >> by LXC :) ? >> >> Is there is anything that I might do about all that? >> >> Thanks and regards, >> Alexandre >> >> >> * Failing tests: shared-memory (rstr), pty2, bash (rstr), script, screen. >> >> >> ------------------------------------------------------------------------------ >> October Webinars: Code for Performance >> Free Intel webinars can help you accelerate application performance. >> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most >> from >> the latest Intel processors and coprocessors. See abstracts and register > >> >> http://pubads.g.doubleclick.net/gampad/clk?id=60134791&iu=/4140/ostg.clktrk >> _______________________________________________ >> Dmtcp-forum mailing list >> dmtcp-fo...@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/dmtcp-forum > > ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60134791&iu=/4140/ostg.clktrk _______________________________________________ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
