[jira] [Created] (BROOKLYN-580) Rebinding to MachineEntity: sometimes fails to reconnect sensor feeds

["Aled Sage (JIRA)" <ji...@apache.org>]

Aled Sage created BROOKLYN-580:
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             Summary: Rebinding to MachineEntity: sometimes fails to reconnect sensor feeds
                 Key: BROOKLYN-580
                 URL: https://issues.apache.org/jira/browse/BROOKLYN-580
             Project: Brooklyn
          Issue Type: Bug
    Affects Versions: 0.12.0
            Reporter: Aled Sage


On rebind, sometimes \{{MachineEntity}} instances do not have their feeds recreated. This is illustrated by non-deterministic test failure in \{{MachineEntityJcloudsRebindTest}}.

The problem is that \{{SoftwareProcessImpl.callRebindHooks}} schedules a task to call \{{connectSensors}} in something between 0 and 10 seconds time, which will try to recreate the feeds. However, if this executes too soon (while rebind is still happening), the \{{SshMachineLocation}} may not yet be managed. If that is the case, the feed is not created.

This is most likely to happen if there are a lot of entities/locations, so iterating over them for rebind takes longer. It is random in that the delay in calling \{{connectSensors}} can sometimes be extremely short (the randomness there is to avoid the thundering herd problem on rebind).

Although the symptoms are similar to https://issues.apache.org/jira/browse/BROOKLYN-425, the underlying cause is different - therefore treating this as a new issue rather than reopening the old one.



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