[mythtv-users] mythweb2 having some more problems

Kevin Ulmes kevinulmes at cybermail.net
Fri Aug 8 11:05:50 EDT 2003


> On Thursday 07 August 2003 09:11 pm, Chris Petersen wrote:
> > > May be a problem with it leaving connections open in the backend, 
> > > but I dunno...
> >
> > why open lots of database connections?  Shouldn't one always-open 
> > connection do the trick?  Just buffer query output when you 
> need to nest
> > loops based on query info..   then again, I'm just talking php/perl
> > speak here - don't know much about the C side of things.
> 
> The mysql client lib isn't threadsafe, and neither is the 
> part of Qt that uses 
> is.  So, I've gotta have one connection per thread that wants 
> to use the 
> database.
> 
> Isaac
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> 

I have noticed in the MySQL process list I've had up to 10 processes
used by MythTV at a time.  Usually all of them are sleeping.  I also
noticed that at any given time I typically have 10 mythbackend threads
running and up to 30 mysqld threads going.  I was wondering if this was
typical of a mythbackend system.  I started to notice the mysqld threads
getting out of control when I started using mythweb2 a few days ago.

I've been able to get rid of this error, by setting a low value for
wait_timeout in mysql.  This doesn't fix the problem, but does get rid
of the symptoms.  I believe that the problem is explained in the
following:

"You are probably using a multi-process web server such as Apache. Since
database connections cannot be shared among different processes a new
one is created if the request happen to come to a different web server
child process."

I found that in the PHP docs online talking about persistent database
connections.  Unfortunately I'm kind of at a loss about how to solve
this one other than switching to non-persistent connections, or setting
a low wait_timeout like I mentioned above.

-Kevin




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