Open Stack

Mark,

On May 2, 2013, at 8:20 AM, Mark Washenberger <mark.washenberger at markwash.net<mailto:mark.washenberger at markwash.net>> wrote:


> This is a workflow (not orchestration) feature and would be solidly in-scope for a WFaaS API (e.g. the proposed https://wiki.openstack.org/wiki/Convection mentioned several times in this thread) in the form of a much more generic "cloud cron" type feature.

Tangentially related, but I just want to get out ahead of the usage of "cron" to describe this type of feature. I think its a bit of a hazard to expose a cron-like interface for clouds, because cron gives the job submitter too much control over the scheduling of their action. This results in problems where a majority of users just pick the default time, or midnight, or 4 AM, which causes strange load spikes in the underlying system.

A better alternative is to express a frequency for the action only, (say 1/day, 1/week, 1/hour, whatever). You can still implement this interface as a cron-like schedule under the covers. But now schedules can be initially randomized, and a cloud administrator can take action if needed to redistribute load.

I agree completely. It's obvious that there's enough interest in this subject to splinter it off into a separate thread, and start designing something that works as a general purpose scheduling tool/resource/service. We have experience with the pitfalls of hosting a very large scale cron system, and understand very well about the situation you've described.

Here is the new thread with a link to a wiki describing a possible Event Scheduling service:

http://lists.openstack.org/pipermail/openstack-dev/2013-May/008510.html

Cheers,

Adrian
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