mpd has hung

[Nikos Vassiliadis]

On 2/17/2010 3:26 PM, Alexander Shikoff wrote:
> Hello All,
>
> I have mpd 5.3 running on 8.0-RC1 as PPPoE server (now only 5 clients).
> Today mpd process hung and I cannot kill it with -9 signal, and I cannot
> access it's console via telnet.
>
> State of process in `top` output is STOP:
> 73551 root          2  44    0 29588K  5692K STOP    6   0:32  0.00% mpd5
>
> # procstat -kk 73551
>    PID    TID COMM             TDNAME           KSTACK
> 73551 100233 mpd5             -                mi_switch+0x16f sleepq_wait+0x42 _cv_wait+0x111 flowtable_flush+0x51 if_detach+0x2f2 ng_iface_shutdown+0x1e ng_rmnode+0x167 ng_apply_item+0xef7 ng_snd_item+0x2ce ngc_send+0x1d2 sosend_generic+0x3f6 kern_sendit+0x13d sendit+0xdc sendto+0x4d syscall+0x1da Xfast_syscall+0xe1
> 73551 100502 mpd5             -                mi_switch+0x16f thread_suspend_switch+0xc6 thread_single+0x1b6 exit1+0x72 sigexit+0x7c postsig+0x306 ast+0x279 doreti_ast+0x1f
>
> Is there a way to stop a process without rebooting a whole system?
> Thanks in advance!
>
> P.S. I'm ready for experiments with it before tonight, but I cannot
> force system to crash in order to get crash dump right now.
>

It's probably too late now, but are you sure that nobody pressed
CTLR-Z while in the mpd console???

CTLR-Z will send SIGSTOP to the process and the process will
stop. While stopped, all processing stops(including receiving
SIGKILL, you cannot kill it, and the signals are queued). You
have to send SIGCONT for the process to continue.

Just a thought, Nikos