Hello Duncan.
On Tue, Mar 25, 2014 at 04:42:56PM +1300, Duncan McEwan wrote:
>
> First, a brief recap. We have a web-based application that runs as a FosWiki
> plugin under Apache/fcgid.
Could you post the fcgid configuration details for us?
https://httpd.apache.org/mod_fcgid/mod/mod_fcgid.html
> The database connection used by this application should be persistent
> due to the application calling DBI->connect_cached() on each invocation.
Persistent within a single backend process, yes.
> The new piece of information that I have discovered recently is that on a
> call to connect_cached() which *doesn't* return the cached database handle,
> the database driver handle reference passed into connect_cached() has changed.
> Since the dbh cache is obtained from "$drh->{CachedKids} ||= {}" I can now
> understand why the cached handled is not found!
>
> What I can't understand is why the driver handle passed into connect_cached()
> has changed!
Neither can I.
> I've got 1000's of lines of debugging showing this happening. Some of it
> is my own, inserted as print statements or cluck calls directly into DBI.pm
> and some of it the standard DBI debugging set to level 9. There is way too
> much to include in this message, but I've included some small extracts below
> to illustrate what I am seeing.
What you've included doesn't show the drh changing.
I suggest you focus on that. Specifically the code path taken by the
request that notices that the drh has changed, _and_ the code path taken
by the _previous_ request _in the same process_.
> One thing I did just notice is that our application calls connect_cached()
> in the way shown in the DBI pod - that is:
>
> my $dbh = DBI->connect_cached(...)
>
> I don't know enough about perl internals to know exactly what this does.
> But I did wonder if something like the following might be better given the
> persistent nature of our application provided by fcgid.
>
> my $dbi = new DBI;
> my $dbh = $dbi->connect_cached(...)
No. Using new DBI (or DBI->new) isn't a valid way to use the DBI.
Just DBI->connect_cached is fine.
Tim.
