[CRIU] Restoring the state of a crashed Java process

[Balakrishnan Chandrasekaran]

Thanks for clarifying.

Bala

On Sep 15, 2014, at 6:19 AM, Pavel Emelyanov <xemul at parallels.com> wrote:

> On 09/13/2014 04:33 AM, Balakrishnan Chandrasekaran wrote:
>> Hi all,
>> 
>> I came across this project just recently, and am impressed with criu. I want to thank all contributors and for keeping it open.
>> 
>> I am trying to run through some examples and understand how to use criu. I ran a simple experiment with a Java 
>> program that maintains a couple of TCP connections with another on the same machine. I took a checkpoint using
>> criu while the connection was open; no data was being exchanged over the connection. If I let the process stop
>> after the checkpointing, I can recover and continue to run the program. However, I let the process run, using 
>> the '-R' option, and try to recover the process from the checkpoint after is crashes (by throwing a RuntimeException), 
> 
> You try to roll-back one end of TCP connection. This is not possible, because the
> peer is not ready to see such time travels :)
> 
>> it doesn't work. I encountered the following error --
>> 
>> --------
>> ip6tables: Bad rule (does a matching rule exist in that chain?).
>> Error (util.c:576): exited, status=1
>> Error (netfilter.c:69): Iptables configuration failed: No such file or directory
>> ip6tables: Bad rule (does a matching rule exist in that chain?).
>> Error (util.c:576): exited, status=1
>> Error (netfilter.c:69): Iptables configuration failed: No such file or directory
> 
> Is this log from CRIU run? When CRIU dumps and restores TCP connection it plays with
> the netfilter rules to lock the connection. If you dump with -R these rules are not
> preserved, while restore expects to see them and tries to turn them off.
> 
>> 09-12-2014 05:25:33.239 ERROR [CPlaneHandler] Connection reset by peer
>> ...
>> 09-12-2014 05:25:33.244 INFO  [AppLoader] Control plane is shutdown
>> 09-12-2014 05:25:33.246 INFO  [AppLoader] Data plane is shutdown
>> bala at galvatron:~/legosdn$ Write failed: Broken pipe
>> --------
>> 
>> Can someone help with resolving this issue? Or, at least tell me, that this is a bad use case for criu,
>> to start with... I do not know much about checkpointing/restore and treating criu as a blackbox, so far,
>> and hence, any pointers would be greatly appreciated.
> 
> Well, as was said, dumping and restoring a TCP connection is only possible in one way --
> dump, kill then restore. Any deviation would cause the peer of the connection to suffer.
> 
> Thanks,
> Pavel

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