id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc	mlocked
10265	mythbackend main thread blocks soon after startup on CentOS 6.2	J. Ali Harlow <ali@…>		"Running fixes/0.24 (294968bea7546d5c0d27b7326401e79a7e67764b) plus [http://code.mythtv.org/trac/attachment/ticket/9704/mythtv-0.24-backport_reconnect_fixes.patch] and mysql-5.1.52-1.el6_0.1.x86_64 on CentOS 6.2

Whenever I start mythbackend, I have a short window to start the frontend during which time it will connect (and appears to work fine). After that short window closes, the backend no longer accepts any connections.

I wrote a simple script/program to show what mythbackend was watching (attached). When I run this during the window, I see something like the following:

{{{
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, 
}}}

A backtrace at this point is attached."	Bug Report - Hang/Deadlock	closed	minor	unknown	MythTV - General	0.24-fixes	medium	Upstream Bug			0