[mythtv-users] MySQL related BE deadlocks - collective wisdom needed
warpme at o2.pl
Tue Aug 30 20:23:10 UTC 2011
On 8/30/11 3:59 PM, Michael T. Dean wrote:
> Out of curiosity--especially for the 0.24-fixes users, but also for
> those using master--how do those of you who are experiencing DB issues
> have your database configured?
> 1) Is your mysqld server running on the same host as the master
> mythbackend server?
> 2) If so, what did you specify for the DBHostName on your master
> mythbackend server's config.xml/mysql.txt file(s)?
> I'm starting to wonder if those of you who are seeing problems may have
> configured DBHostName to use a host name or routable IP address--which
> forces Qt-MySQL drivers to use a TCP/IP connection to the MySQL server
> using the network stack. If, at some point, certain tools on certain
> distros detect a network issue, they will unconfigure the entire network
> (even removing the IP address from the NIC)--basically, they rip the
> entire network out from under all running applications. For an
> application that requires a reliable connection to a database, this
> means Bad Things happen.
> Because of this, I recommend a) running the mysqld server on the master
> backend host and b) using localhost for the DBHostName in the
> config.xml/mysql.txt for the master backend host, only. Please see
> http://www.gossamer-threads.com/lists/mythtv/users/490328#490328 for
> information--and note that you can use localhost for /only/ the
> DBHostName in a multi-host setup (you cannot use localhost/127.0.0.1/::1
> for the this backend/master backend "IP Address" settings).
> If you've been having issues with MySQL disappearing on you, I'd
> appreciate your replying with answers to the 2 questions, above. If you
> do have a system with mysqld running on the master mythbackend host, and
> it's not already, please try changing DBHostName to localhost to see if
> it improves stability (or fixes the issue for you).
> mythtv-users mailing list
> mythtv-users at mythtv.org
It is great You are trying trace mysql reconnect issue.
Sometime ago I had hypothesis related server<->lib comm.aspect, so I
move Qt-mysgl lib.comm from unix socket to TCP/IP.
After few days of tests I didn't any change in reconnects
density/distribution in time.
In fact my experience is that os upgrade had clearly noticeable impact
on reconnects density/distribution: avg.1 per day vs avg.1 per 5 days.
This was on short observation window (6 days) so it might be pure hazard
Answering Your questions:
a\yes. My DB is on the master be host
b\my DB server talks with client lib via unix socket
Now I switch from Dillon's cron (as it is dead proj.from 2y) to dcron,
make sure all my cron jobs are under my full control and begin next
long-term testing window.
I will report result as soon as something interesting pops-up or after 3
weeks if all will be OK (well, I strongly hope for latter).
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