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| Release Notes for Apache Helix 0.8.2 |
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| Release Notes for Apache Helix 0.8.2 |
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| The Apache Helix team would like to announce the release of Apache Helix 0.8.2. |
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| This is the fourteenth release under the Apache umbrella, and the tenth as a top-level project. |
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| Helix is a generic cluster management framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. |
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| In this release, Helix provides several performance improvements for rebalance pipeline: |
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| [] |
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| * Detailed Changes |
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| ** New Features |
| * [ROUTER] Expose ExternalViews in RoutingTable and RoutingTableSnapshot |
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| * [TASK] Expose UserContentStore in TaskDriver |
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| * [TASK] Add ThreadCountBasedAssignmentCalculator and integrate with Workflow/JobRebalancer and fix rebalancing logic |
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| * Should not start periodical refresh in RoutingTableProvider if helixmanager is not set. |
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| * Allow downward state transition during recovery and add recovery threshold |
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| * Support batch add jobs to JobQueue |
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| * Add periodic refresh to RoutingTableProvider |
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| ** Bug Fixes |
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| * Make swap instance more robust and idempotent |
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| * Fix the issue that resource MBean may not be cleaned up when the resource is dropped. |
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| * Check NPE in getInstancesInClusterWithTag and throw more meaningful exception |
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| * Fix GroupCommit issue for adding back current state |
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| * Fix zkclient state related check and some potential bugs. |
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| * Fix race condition in Helix messaging service. |
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| * Fix bugs in ClusterStateVerifier and StrictMatchExternalViewVerifier. |
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| * Verify downward load balance and fix TestPartitionMovementThrottle |
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| ** Improvements |
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| * Adding RoutingTableProvider monitor for tracking refresh actions and routing table update callbacks. |
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| * Helix manager should support getting metadata store connection string |
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| * Add missing replica partition metric into ClusterStatus. |
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| * Improve BestPossibleExternalViewVerifier by avoid fully refreshing entire cluster data everytime and avoid to calulate bestpossible states for not required resources. |
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| * Support event differentiated logging |
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| * Helix job should fail immediately if the target resource is disabled |
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| * Make ZkClient keep retrying connect on expiring. |
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| * DelayedAutoRebalancer should calculate assignment based on full partition list. |
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| * Change RoutingDataCache to use zk version based selective update when reading the ExternalViews and TargetExternalView. |
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| * Change migration strategy to N -> N+1 -> N model |
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| * Add ThreadPoolExecutor purge and shutdown to avoid memory leak in RoutingTableProvider |
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| [] |
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| Cheers, |
| -- |
| The Apache Helix Team |