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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-8714) Suggest new users to use env.readTextFile method with 2 arguments (using the charset), not to rely on system charset (which varies across environments)
Date Fri, 23 Feb 2018 13:30:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-8714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16374341#comment-16374341
] 

ASF GitHub Bot commented on FLINK-8714:
---------------------------------------

Github user michalklempa commented on the issue:

    https://github.com/apache/flink/pull/5536
  
    @zentol Thanks, done.


> Suggest new users to use env.readTextFile method with 2 arguments (using the charset),
not to rely on system charset (which varies across environments)
> -------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-8714
>                 URL: https://issues.apache.org/jira/browse/FLINK-8714
>             Project: Flink
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 1.4.0
>            Reporter: Michal Klempa
>            Priority: Trivial
>              Labels: easyfix, newbie, patch-available
>
> When a newcomer (like me), goes through the docs, there are several places where examples
encourage to read the input data using the {{env.readTextFile()}} method.
>  
> This method variant does not take a second argument - character set (see [https://ci.apache.org/projects/flink/flink-docs-release-1.4/api/java/org/apache/flink/streaming/api/environment/StreamExecutionEnvironment.html#readTextFile-java.lang.String-).]
This versoin relies (according to Javadoc) on " The file will be read with the system's default
character set. "
>  
> This behavior is also default in Java, like in the {{java.util.String.getBytes()}} method,
where not supplying the charset mean - use the system locale or the one which JVM was started
with (see [https://stackoverflow.com/questions/64038/setting-java-locale-settings).] There
are two ways to set locale prior to JVM start (-D arguments or set LC_ALL variable).
>  
> Given this is something a new Flink user may not know about, nor he wants to spend hours
trying to find the environment-related bug (it works on localhost, but in production the locale
is different), I would kindly suggest a change in documentation: lets migrate examples to
use the two-argument version of {{readTextFile(filePath, charsetName)}}.
>  
> I am open to criticism and suggestions. The listing of {{readTextFile}} I was able to
grep in docs is:
> {code:java}
> ./dev/datastream_api.md:- `readTextFile(path)` - Reads text files, i.e. files that respect
the `TextInputFormat` specification, line-by-line and returns them as Strings.
> ./dev/datastream_api.md:- `readTextFile(path)` - Reads text files, i.e. files that respect
the `TextInputFormat` specification, line-by-line and returns them as Strings.
> ./dev/libs/storm_compatibility.md:DataStream<String> text = env.readTextFile(localFilePath);
> ./dev/cluster_execution.md:    DataSet<String> data = env.readTextFile("hdfs://path/to/file");
> ./dev/batch/index.md:- `readTextFile(path)` / `TextInputFormat` - Reads files line wise
and returns them as Strings.
> ./dev/batch/index.md:- `readTextFileWithValue(path)` / `TextValueInputFormat` - Reads
files line wise and returns them as
> ./dev/batch/index.md:DataSet<String> localLines = env.readTextFile("file:///path/to/my/textfile");
> ./dev/batch/index.md:DataSet<String> hdfsLines = env.readTextFile("hdfs://nnHost:nnPort/path/to/my/textfile");
> ./dev/batch/index.md:DataSet<String> logs = env.readTextFile("file:///path/with.nested/files")
> ./dev/batch/index.md:- `readTextFile(path)` / `TextInputFormat` - Reads files line wise
and returns them as Strings.
> ./dev/batch/index.md:- `readTextFileWithValue(path)` / `TextValueInputFormat` - Reads
files line wise and returns them as
> ./dev/batch/index.md:val localLines = env.readTextFile("file:///path/to/my/textfile")
> ./dev/batch/index.md:val hdfsLines = env.readTextFile("hdfs://nnHost:nnPort/path/to/my/textfile")
> ./dev/batch/index.md:env.readTextFile("file:///path/with.nested/files").withParameters(parameters)
> ./dev/batch/index.md:DataSet<String> lines = env.readTextFile(pathToTextFile);
> ./dev/batch/index.md:val lines = env.readTextFile(pathToTextFile)
> ./dev/batch/examples.md:DataSet<String> text = env.readTextFile("/path/to/file");
> ./dev/batch/examples.md:val text = env.readTextFile("/path/to/file")
> ./dev/api_concepts.md:DataStream<String> text = env.readTextFile("file:///path/to/file");
> ./dev/api_concepts.md:val text: DataStream[String] = env.readTextFile("file:///path/to/file")
> ./dev/local_execution.md:    DataSet<String> data = env.readTextFile("file:///path/to/file");
> ./ops/deployment/aws.md:env.readTextFile("s3://<bucket>/<endpoint>");{code}
>  



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