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https://issues.apache.org/jira/browse/BROOKLYN-285?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15307414#comment-15307414
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Aled Sage commented on BROOKLYN-285:
------------------------------------
This behaviour has likely already been changed in Brooklyn master, as a result
of fixing https://issues.apache.org/jira/browse/BROOKLYN-278 (see
https://github.com/apache/brooklyn-server/pull/154). We still need to confirm
if it is fixed.
> Dangling reference in Propagator.producer: can cause subscription to self,
> and infinite subscription loop
> ---------------------------------------------------------------------------------------------------------
>
> Key: BROOKLYN-285
> URL: https://issues.apache.org/jira/browse/BROOKLYN-285
> Project: Brooklyn
> Issue Type: Bug
> Affects Versions: 0.9.0
> Reporter: Aled Sage
>
> When the "producer" entity of a Propagator enricher is unmanaged, it can
> cause rebind to resolve the dangling reference value as {{null}}. In 0.9.0,
> that is treated as the producer being "self". This can cause an infinite
> loop, where the Propagator subscribes to its own sensor, and every time its
> sensor changes it resets the sensor value.
> To reproduce, deploy this app:
> {noformat}
> location: localhost
> services:
> - type: org.apache.brooklyn.entity.stock.BasicApplication
> brooklyn.children:
> - type: org.apache.brooklyn.entity.machine.MachineEntity
> {noformat}
> And programmatically add a Propagator enricher to the top-level app, such as:
> {noformat}
> appId = "u4VDoIOa";
> childId = "LPYT4g27";
> sensor = org.apache.brooklyn.core.sensor.Sensors.newSensor(String.class,
> "host.name");
> app = mgmt.getEntityManager().getEntity(appId);
> child = mgmt.getEntityManager().getEntity(childId);
> app.enrichers().add(org.apache.brooklyn.api.sensor.EnricherSpec.create(org.apache.brooklyn.enricher.stock.Propagator.class)
> .configure("enricher.producer", child)
> .configure("enricher.propagating.inclusions",
> com.google.common.collect.ImmutableList.of(sensor)));
> {noformat}
> Then unmanange the child entity (e.g. via the advanced tab in the
> web-console), and restart Brooklyn.
> The CPU goes through the roof, and the debug log shows log messages like:
> {noformat}
> 2016-05-31 09:02:22,599 DEBUG o.a.b.c.m.i.LocalSubscriptionManager
> [brooklyn-execmanager-gfOvVoKq-3]: 388000 events for subscriber
> Subscription[qF9YFEBA;BasicApplicationImpl{id=u4VDoIOa}@u4VDoIOa:host.name]
> {noformat}
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