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https://issues.apache.org/jira/browse/FLINK-9113?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16428297#comment-16428297
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ASF GitHub Bot commented on FLINK-9113:
---------------------------------------
Github user pnowojski commented on a diff in the pull request:
https://github.com/apache/flink/pull/5811#discussion_r179743870
--- Diff:
flink-connectors/flink-connector-filesystem/src/main/java/org/apache/flink/streaming/connectors/fs/bucketing/BucketingSink.java
---
@@ -366,6 +384,11 @@ public void
initializeState(FunctionInitializationContext context) throws Except
throw new RuntimeException("Error while creating
FileSystem when initializing the state of the BucketingSink.", e);
}
+ // sync on flush for local file systems
+ if (localSyncOnFlush && (fs instanceof LocalFileSystem) &&
(writerTemplate instanceof StreamWriterBase)) {
--- End diff --
Shouldn't `(writerTemplate instanceof StreamWriterBase)` check be converted
here into `checState(writerTemplate instanceof StreamWriterBase)` inside the if
branch, and the same check be extracted and validated whenever user calls:
`setWriter(...)` or `setLocalSyncOnFlush(...)`? So that non
`StreamWriterBase` and `localSyncOnFlush = true` would be invalid
configuration? Otherwise users might experience `wtf` moments when flag is
being ignored after changing their writer.
> Data loss in BucketingSink when writing to local filesystem
> -----------------------------------------------------------
>
> Key: FLINK-9113
> URL: https://issues.apache.org/jira/browse/FLINK-9113
> Project: Flink
> Issue Type: Bug
> Components: Streaming Connectors
> Reporter: Timo Walther
> Assignee: Timo Walther
> Priority: Major
>
> This issue is closely related to FLINK-7737. By default the bucketing sink
> uses HDFS's {{org.apache.hadoop.fs.FSDataOutputStream#hflush}} for
> performance reasons. However, this leads to data loss in case of TaskManager
> failures when writing to a local filesystem
> {{org.apache.hadoop.fs.LocalFileSystem}}. We should use {{hsync}} by default
> in local filesystem cases and make it possible to disable this behavior if
> needed.
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