[wp-hackers] Database connection drops

[David Anderson]

Hi,

It's amazing how slow some people's web hosting is. I'm currently 
looking at a log file of a backup of a site which takes over an hour to 
create a single 150Mb zip file (which does have 26,000 files in it).

It appears that after somewhere around 3000 seconds, the database 
connection is dropped, and all commands that result in talking to the 
database silently fail. For example, this returns no results:

$all_tables = $wpdb->get_results("SHOW TABLES", ARRAY_N);

As another example, the option which my code is using to save its state 
isn't updated after that time. The saved state is out-of-date. (At this 
point, that's not a huge problem, as I have lots of checks and balances).

If I use the scheduler to schedule a restart of the task a few seconds 
later, then everything works. $wpdb isn't getting over-written, as that 
would lead to fatal errors for methods not found instead of silent failure.

Has anyone come across something like that before? Does anyone know 
where in WordPress core this happens...

... and the important question: how to detect it/refresh the connection 
when it happens? At the moment I've thrown in a quick check at a key 
point, but on the test case I've seen, that comes about 10 minutes late. 
That's no problem, as everything in the code I've written is resumable 
and can detect and recover from failures like this. It'd just be good to 
not waste 10 minutes though.

Many thanks,
David

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