Problems with Cached DBI connections

Tom Insam tom at
Tue Nov 14 12:33:29 GMT 2006

On Nov 13, 2006, at 22:09, Dave Hodgkinson wrote:

> On 13 Nov 2006, at 19:30, Simon Wistow wrote:
>> Has anybody else seen a phenomenom where they're using cached DBI
>> connections but N processes run out of connections despite the  
>> fact that
>> the DB (in this case MySQL - not sure if that's relevant) has a
>> connection limit of M where N<M?
> Are you using a variety of credentials to connect? If so, each
> username/database combo uses a connection.

I was once bitten by a custom error handler subroutine on my connect  
call - something like

my $dbh = DBI->connect_cached( ...
   HandleError => sub {
     my $error = shift;

Because _all_ the params to connect_cached are used to decide that  
this should be a distinct connection, and the sub {} is an anonymous  
that gets redefined every time you call the connect call, this lead  
quickly to every apache process making 2000 database connections, and  
never letting any of them go.



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