[jira] [Commented] (FLINK-9373) Always call RocksIterator.status() to check the internal error of RocksDB

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-9373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16477035#comment-16477035
 ] 

ASF GitHub Bot commented on FLINK-9373:
---

Github user sihuazhou commented on the issue:

https://github.com/apache/flink/pull/6020
  
cc @StefanRRichter 


> Always call RocksIterator.status() to check the internal error of RocksDB
> -
>
> Key: FLINK-9373
> URL: https://issues.apache.org/jira/browse/FLINK-9373
> Project: Flink
>  Issue Type: Bug
>  Components: State Backends, Checkpointing
>Affects Versions: 1.5.0
>Reporter: Sihua Zhou
>Assignee: Sihua Zhou
>Priority: Blocker
>
> Currently, when using RocksIterator we only use the _iterator.isValid()_ to 
> check whether we have reached the end of the iterator. But that is not 
> enough, if we refer to RocksDB's wiki 
> https://github.com/facebook/rocksdb/wiki/Iterator#error-handling we should 
> find that even if _iterator.isValid()=true_, there may also exist some 
> internal error. A safer way to use the _RocksIterator_ is to always call the 
> _iterator.status()_ to check the internal error of _RocksDB_. There is a case 
> from user email seems to lost data because of this 
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Missing-MapState-when-Timer-fires-after-restored-state-td20134.html



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[jira] [Commented] (FLINK-9373) Always call RocksIterator.status() to check the internal error of RocksDB

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-9373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16476989#comment-16476989
 ] 

ASF GitHub Bot commented on FLINK-9373:
---

GitHub user sihuazhou opened a pull request:

https://github.com/apache/flink/pull/6020

[FLINK-9373][state] Always call RocksIterator.status() to check the 
internal error of RocksDB

## What is the purpose of the change

Currently, when using RocksIterator we only use the `iterator.isValid()` to 
check whether we have reached the end of the iterator. But that is not enough, 
if we refer to RocksDB's wiki 
https://github.com/facebook/rocksdb/wiki/Iterator#error-handling we should find 
that even if `iterator.isValid()=true`, there may also exist some internal 
errors. A safer way to use the `RocksIterator` is to always call the 
`iterator.status()` to check the internal error of RocksDB. There is one case 
from user email seems to lost data because of this 
http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Missing-MapState-when-Timer-fires-after-restored-state-td20134.html
 (I'm not so sure yet)

## Brief change log

  - *Always call RocksIterator.status() to check the internal error of 
RocksDB*


## Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

## Does this pull request potentially affect one of the following parts:

  - Dependencies (does it add or upgrade a dependency): (no)
  - The public API, i.e., is any changed class annotated with 
`@Public(Evolving)`: (no)
  - The serializers: (no)
  - The runtime per-record code paths (performance sensitive): (no)
  - Anything that affects deployment or recovery: JobManager (and its 
components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
  - The S3 file system connector: (no)

## Documentation

  - Does this pull request introduce a new feature? (no)


You can merge this pull request into a Git repository by running:

$ git pull https://github.com/sihuazhou/flink FLINK-9373

Alternatively you can review and apply these changes as the patch at:

https://github.com/apache/flink/pull/6020.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

This closes #6020


commit b1d531949d521bb7d72cd389dfe72a4a5cf1bfc9
Author: sihuazhou 
Date:   2018-05-16T07:47:05Z

Always call RocksIterator.status() to check the internal error of RocksDB




> Always call RocksIterator.status() to check the internal error of RocksDB
> -
>
> Key: FLINK-9373
> URL: https://issues.apache.org/jira/browse/FLINK-9373
> Project: Flink
>  Issue Type: Bug
>  Components: State Backends, Checkpointing
>Affects Versions: 1.5.0
>Reporter: Sihua Zhou
>Assignee: Sihua Zhou
>Priority: Blocker
>
> Currently, when using RocksIterator we only use the _iterator.isValid()_ to 
> check whether we have reached the end of the iterator. But that is not 
> enough, if we refer to RocksDB's wiki 
> https://github.com/facebook/rocksdb/wiki/Iterator#error-handling we should 
> find that even if _iterator.isValid()=true_, there may also exist some 
> internal error. A safer way to use the _RocksIterator_ is to always call the 
> _iterator.status()_ to check the internal error of _RocksDB_. There is a case 
> from user email seems to lost data because of this 
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Missing-MapState-when-Timer-fires-after-restored-state-td20134.html



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