[CRIU] I can't dump mysqld

[Dmitry Safonov]

On 07/27/2016 10:21 AM, uhoi wrote:
> Hi, everyone.

Hi,

> I tried to dump mysqld, but I could not do so well.
> I executed the followed command.
>
> criu dump -t mysqld_pid -D ${CHECKPOINT} -v4 -o dump.log --file-locks
>
> This command was not finished.
> I think that criu stopped or did an infinite loop.
> I can't find any errors in dump.log.
>
> I tried to set up my.cnf In reference to　https://lists.openvz.org
> /pipermail/criu/2014-April/013425.html
> and I turned off innodb_use_native_aio. However criu stopped...
>
> I can't understand what happened.
> Please give me any advise...
>
> [dump.log]
...
> (00.369533) Parasite syscall_ip at 0x400000
> (00.369825) Set up parasite blob using memfd
> (00.369833) Putting parasite blob into 0x7f2ec821f000->0x7f1ce412a000
> (00.369854) Dumping GP/FPU registers for 8367
> (00.369859) Warn  (arch/x86/crtools.c:132): Will restore 8367 with
> interrupted system call
> (00.369868) xsave runtime structure
> (00.369871) -----------------------
> (00.369874) cwd:37f swd:0 twd:0 fop:0 mxcsr:1fa0 mxcsr_mask:ffff
> (00.369884) magic1:0 extended_size:0 xstate_bv:0 xstate_size:0
> (00.369888) xstate_bv: 0
> (00.369891) -----------------------
> (00.369895) Putting tsock into pid 8367

It looks like, criu is waiting for parasite in your application to
establish connection on a socket. For some reason parasite does not
finish that.
We could get more info, if you do the following:
$ cat /proc/${mysqld_pid}/stack
$ cat /proc/${criu_pid}/stack

Also it would be worth to know criu version (it looks like it's some
from master branch, but we don't print exact version in logs yet).

I think to improve this kinds of faults, we could introduce another
alarm in CRIU which would cure task and print error in case if the
connection hasn't been established for some reson.

-- 
              Dmitry