| = 16. Distributed WorkQueue |
| |
| Date: 2019-12-03 |
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| == Status |
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| Accepted (lazy consensus) |
| |
| Supercedes xref:0003-distributed-workqueue.adoc[3. |
| Distributed WorkQueue] |
| |
| == Context |
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| By switching the task manager to a distributed implementation, we need to be able to run a `Task` on any node of the cluster. |
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| == Decision |
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| For the time being we will keep the sequential execution property of the task manager. |
| This is an intermediate milestone toward the final implementation which will drop this property. |
| |
| * Use a RabbitMQ queue as a workqueue where only the `Created` events are pushed into. |
| Instead of using the brittle exclusive queue mechanism described in xref:0003-distributed-workqueue.adoc[3. |
| Distributed WorkQueue], we will now use the natively supported https://www.rabbitmq.com/consumers.html#single-active-consumer[Single Active Consumer] mechanism. |
| |
| == Consequences |
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| * This solution is safer to use in production: if the active consumer dies, an other one is promoted instead. |
| * This change needs RabbitMQ version to be at least 3.8.0. |
| * The serial execution of tasks still does not leverage cluster scalability. |
