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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-8360) Implement task-local state recovery
Date Fri, 05 Jan 2018 14:03:01 GMT

    [ https://issues.apache.org/jira/browse/FLINK-8360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16313145#comment-16313145
] 

ASF GitHub Bot commented on FLINK-8360:
---------------------------------------

Github user pnowojski commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5239#discussion_r159840618
  
    --- Diff: flink-contrib/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBKeyedStateBackend.java
---
    @@ -831,11 +834,12 @@ private StreamStateHandle materializeStateData(Path filePath) throws
Exception {
     				return result;
     
     			} finally {
    -				if (inputStream != null && closeableRegistry.unregisterCloseable(inputStream))
{
    +
    +				if (closeableRegistry.unregisterCloseable(inputStream)) {
     					inputStream.close();
     				}
     
    -				if (outputStream != null && closeableRegistry.unregisterCloseable(outputStream))
{
    +				if (closeableRegistry.unregisterCloseable(outputStream)) {
    --- End diff --
    
    Side note, I do not understand why there is a `try` `finally` block with `close()` AND
additional `closeableRegistry`. Is `closeableRegistry` used for artificially interrupting
reads/writes?
    
    Anyway, could you add some comment explaining this to the `closeableRegistry` field declaration?



> Implement task-local state recovery
> -----------------------------------
>
>                 Key: FLINK-8360
>                 URL: https://issues.apache.org/jira/browse/FLINK-8360
>             Project: Flink
>          Issue Type: New Feature
>          Components: State Backends, Checkpointing
>            Reporter: Stefan Richter
>            Assignee: Stefan Richter
>             Fix For: 1.5.0
>
>
> This issue tracks the development of recovery from task-local state. The main idea is
to have a secondary, local copy of the checkpointed state, while there is still a primary
copy in DFS that we report to the checkpoint coordinator.
> Recovery can attempt to restore from the secondary local copy, if available, to save
network bandwidth. This requires that the assignment from tasks to slots is as sticky is possible.
> For starters, we will implement this feature for all managed keyed states and can easily
enhance it to all other state types (e.g. operator state) later.



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