[mythtv-commits] Ticket #10188: Deadlocks constantly
MythTV
noreply at mythtv.org
Sat Jan 14 17:50:58 UTC 2012
#10188: Deadlocks constantly
----------------------------------------+----------------------------
Reporter: yurko@… | Owner:
Type: Bug Report - Hang/Deadlock | Status: new
Priority: major | Milestone: unknown
Component: MythTV - General | Version: Trunk Head
Severity: medium | Resolution:
Keywords: Dead Lock | Ticket locked: 0
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Comment (by J. Ali Harlow <ali@…>):
I wrote a little script/program to see what the backend is watching at any
time which might help somebody work out what's going on. Shortly after
restarting the backend, I get something like this:
{{{
22280: poll fds=[{fd=3, events=1, revents=0} {fd=9, events=1, revents=0}
{fd=38, events=1, revents=0} {fd=3, events=1, revents=0}] nfds=0x4
22285: poll fds=[{fd=7, events=1, revents=0}] nfds=0x1
22288: select nfds=0xf readfds=[12 13 14] writefds=0x0 exceptfds=0x0
22444: poll fds=[{fd=26, events=1, revents=0}] nfds=0x1
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mythbacke 22280 root 3r FIFO 0,8 0t0 117605 pipe
mythbacke 22280 root 7r FIFO 0,8 0t0 117615 pipe
mythbacke 22280 root 9u IPv4 117616 0t0 TCP *:lds-dump
(LISTEN)
mythbacke 22280 root 12u IPv4 117619 0t0 UDP *:apc-6549
mythbacke 22280 root 13u IPv4 117620 0t0 UDP
239.255.255.250:ssdp
mythbacke 22280 root 14u IPv4 117621 0t0 UDP
255.255.255.255:ssdp
mythbacke 22280 root 26r FIFO 0,8 0t0 118008 pipe
mythbacke 22280 root 38u IPv4 118014 0t0 TCP *:lds-distrib
(LISTEN)
}}}
so we can see that the main thread is watching some pipe (twice) and the
two listening TCP ports.
A little later, we get this:
{{{
22285: poll fds=[{fd=7, events=1, revents=0}] nfds=0x1
22288: select nfds=0xf readfds=[12 13 14] writefds=0x0 exceptfds=0x0
22444: poll fds=[{fd=26, events=1, revents=0}] nfds=0x1
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mythbacke 22280 root 7r FIFO 0,8 0t0 117615 pipe
mythbacke 22280 root 12u IPv4 117619 0t0 UDP *:apc-6549
mythbacke 22280 root 13u IPv4 117620 0t0 UDP
239.255.255.250:ssdp
mythbacke 22280 root 14u IPv4 117621 0t0 UDP
255.255.255.255:ssdp
mythbacke 22280 root 26r FIFO 0,8 0t0 118008 pipe
}}}
and strace tells us the main thread is blocked reading the pipe that it
was watching:
{{{
# strace -p 22280
Process 22280 attached - interrupt to quit
read(3,
}}}
It seems this read never returns.
--
Ticket URL: <http://code.mythtv.org/trac/ticket/10188#comment:13>
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