Re: [SQLObject] Enduring long queries outside SQLObject

[Ian B. <ia...@co...>]

On Nov 6, 2003, at 12:44 PM, Frank Barknecht wrote:
> I have to feed my database via a CSV-file from the outside world.
> Loading the CSV via Mysql's "load data infile..." query takes a rather
> long time and, maybe more importantly, invalidates several SQLObject
> instances. This leads to errors in the Webware application I'm
> running, where SQLObjects are called, until the Webware AppServer
> eventually hangs.  The outside query has a duration of about 10
> seconds for 55,000 rows.

Well, you could try locking SQLObject instance access while you're 
loading the CSV file, if there's a concurrency issue.  I think you 
could do this in MySQLConnection, maybe in the _query method (i.e., 
check for a lock and wait until it is released).

> Now I'm contemplating strategies against this. I'm not quite sure
> where the problems lie, though. The only real "solution" I have is
> restarting the Webware AppServer, but I wonder, if I could just as
> well "restart" my SQLObjects somehow.

Using 0.5 you should be able to .expire() the instances.  
DBConnection.Transaction.rollback does this, and you could probably 
separate that code out, maybe make an expireAll method on DBConnection 
instances.  Ultimately that method should also find all sub-connections 
(i.e., transactions), each of which have their own cache and set of 
instances, but that's probably not an issue for you using MySQL.

> (And, slightly off-topic here, but I know, many here use Webware: How
> do I restart Webware's Appserver in an elegant way from inside
> Webware?)

Look at the auto-reloader.  I can't remember off the top of my head how 
it works, but I think it just sets a flag in the Application which 
causes it to restart.  But if you have stalled threads this won't work, 
the only way to restart then is to kill -9.

--
Ian Bicking | ia...@co... | http://blog.ianbicking.org