Petrusko:
Probably there is a memory leakage somewhere that makes everything fail and get process eventually killed by OS.
You're right Ivan, my bad ! Swap has grown quickly and has been full... Ok, it was a test with another instance... so I'll kill this other instance :(
There is nothing wrong at your side. You're probably experiencing the same issue as in ticket I've mentioned earlier. "a memory leakage somewhere" means that this "somewhere" is a place in tor code and probably triggered remotely. This definitely ought to be fixed since it may be a DoS vulnerability (process crash). So if you have some details on this issue please report them to the mentioned ticket.
Thanks, -- Ivan Markin