[wp-trac] [WordPress Trac] #17462: Improve cron locking

[WordPress Trac]

#17462: Improve cron locking
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 Reporter:  ryan          |       Owner:
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Future Release
Component:  Cron          |     Version:  3.1.2
 Severity:  normal        |  Resolution:
 Keywords:  has-patch     |
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Comment (by Denis-de-Bernardy):

 Replying to [comment:3 nacin]:
 > Short discussion in IRC with duck_ and ryan led to this suggestion that
 I think we all liked: Make the timeout longer and clear the transient when
 wp-cron.php completes.

 Can't this lead to runaway crons just like the current situation?

 Suppose you've a batch of 100k registration emails to send, and a fussy
 shared host that kills lengthy processes. Cron A locks and starts sending
 emails. The next couple of crons see things are locked so don't start.
 Server kills cron A because it's taking too long. Cron B locks and starts
 sending emails (to the same people). The next couple of crons see things
 are locked (etc.).

 To avoid the problem, locking needs to be done for individual cron jobs,
 rather than as a group. This would allow to mark individual items as being
 locked/in progress, and concurrent crons could then kick in and process
 other items accordingly.

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Ticket URL: <http://core.trac.wordpress.org/ticket/17462#comment:4>
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