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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/50636/
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Review request for Ambari, Alejandro Fernandez, Nate Cole, Robert Levas, and
Sid Wagle.
Bugs: AMBARI-17970
https://issues.apache.org/jira/browse/AMBARI-17970
Repository: ambari
Description
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This was an EclipseLink cache problem discovered on downgrade testing. When
downgrading Ranger Admin from HDP 2.5 to HDP 2.4, the python code correctly
detects HDP 2.4 is the version it should use for "stack feature" checking. On
HDP 2.4, Ranger used the audit DB and therefore looks at the configs for audit
DB related data.
However, the data was not there. The problem is complex, yet subtle:
- The client thread creating the downgrade changes the desired configurations
of the cluster (that's good!)
- The action scheduler picks up the first task to run during downgrade and sees
that configs need to be refresh (that's good!)
- The ClusterEntity that the action scheduler sees from its entity manager
doesn't have the updates applied by the client thread (that's bad!)
It takes EclipseLink up to 1000ms to invalidate the L1 persistence context
cache of the action scheduler's EntityManager. As a result, there's a fraction
of a second where the scheduler could see the first downgrade task and try to
schedule it using stale configurations. In this case, the configurations from
HDP 2.5.
The solution I chose was to use a synchronous event bus to instruct interested
DAOs to invalidate particular entities. The entity manager bound to the action
scheduler thread was the problem, but since that thread uses so many DAOs
indirectly, it was easier to broadcast an event to interested DAOs, keeping the
scheduler thread out of it.
Diffs
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ambari-server/src/main/java/org/apache/ambari/server/actionmanager/ExecutionCommandWrapper.java
2f6ab02
ambari-server/src/main/java/org/apache/ambari/server/events/jpa/EntityManagerCacheInvalidationEvent.java
PRE-CREATION
ambari-server/src/main/java/org/apache/ambari/server/events/jpa/JPAEvent.java
PRE-CREATION
ambari-server/src/main/java/org/apache/ambari/server/events/publishers/JPAEventPublisher.java
PRE-CREATION
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/ClusterDAO.java
7f499f0
ambari-server/src/main/java/org/apache/ambari/server/state/cluster/ClusterImpl.java
53059dc
ambari-server/src/test/java/org/apache/ambari/server/state/cluster/ClusterTest.java
7c0e17c
Diff: https://reviews.apache.org/r/50636/diff/
Testing
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PENDING UNIT TESTS
Thanks,
Jonathan Hurley
