[support] Cron and clearing caches to update field data..

[Earnie Boyd]

On Tue, Oct 2, 2012 at 7:11 AM, Wipe_Out wrote:
> Hi,
>
> Can someone explain what running the drupal cron job does and at what
> intervals??
>

http://drupal.org/cron

> Here is the situation.. We are updating a particular field directly in the
> database from another source.. This is working fine but the issue is that
> the updated information doesn't show on the site straight away..
>
> I have cron running every hour and have the cache lifetimes on the
> performance page set to 10 min but even after waiting an hour and a cron run
> the page still isn't always updated with the new value of the field..
> Sometimes it is and sometimes it isn't..
>

Each module may have a cron hook implementation.  The cron.php process
gets 240 seconds to execute those cron hook implementations.  If the
240 seconds time limit is exceeded then it is possible that some cron
hook implementations do not execute or complete.  I tend to use a 5
minute cycle and use Elysia Cron module to adjust which cron hook
implementations run at various times.

> The only way I have found to "force" an update is to clear all the caches
> but this seems like a massive overkill..
>

May strictly be a timing issue.  I don't know but usually these
effects for me tend to be related to my impatience or a lack of
understanding in the flow.

> If I can find out when it will update on its own I can set the user
> expectations so they know they have to wait that long for the data to be
> updated..
>

As explained above, you may be exceeding the 240 second cycle before
the cron hook implementation executes.  The experience will be
variable even with my suggestion of every 5 minutes and Elysia cron.

> Thanks for any information..

HTH.

-- 
Earnie
-- https://sites.google.com/site/earnieboyd