[wp-hackers] Transients that are not re-used after their expiry are never garbage-collected

[James Collins]

Hi Otto,

On 3 May 2013 23:34, Otto <otto at ottodestruct.com> wrote:

> Why would you have a transient with a unique key? Or a key that
> changes? This sort of defeats the point of using a transient in the
> first place.


The WP e-Commerce plugin includes what I think is a valid use case for
unique transient keys: [1].

The Australia Post API responses are cached using transients, and the cache
key(s) depend on the volume/dimensions/destination of each customer's cart
contents, which means there can be quite a few different transient cache
keys on each store.

[1]
https://github.com/wp-e-commerce/WP-e-Commerce/blob/master/wpsc-shipping/australiapost.php#L284


James




On 3 May 2013 23:34, Otto <otto at ottodestruct.com> wrote:

> Why would you have a transient with a unique key? Or a key that
> changes? This sort of defeats the point of using a transient in the
> first place.
>
> Sounds to me like you should fix the code that is using transients
> incorrectly.
>
> -Otto
>
>
> On Fri, May 3, 2013 at 4:18 AM, David Anderson <david at wordshell.net>
> wrote:
> > Hi,
> >
> > Just a heads-up for others who may not be aware of this - I was not until
> > today, until I began to look at my options table with ~250,000 entries
> in it
> > (after 2 months!)...
> >
> > WordPress does not garbage-collect transients unless you attempt to
> access
> > them. This means that if you use transients with unique keys, or keys
> that
> > are not expected to be used after a certain time (e.g. as access tokens),
> > then they may never be purged.
> >
> > Here's a simple plugin to provide temporary relief until this is fixed in
> > core:
> > http://downloads.wordpress.org/plugin/artiss-transient-cleaner.1.1.zip
> >
> > Trac ticket for the issue:
> > http://core.trac.wordpress.org/ticket/20316#comment:16
> >
> > Best wishes,
> > David
> >
> > --
> > WordShell - WordPress fast from the CLI - www.wordshell.net
> >
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