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https://issues.apache.org/jira/browse/FLINK-8714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16370075#comment-16370075
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ASF GitHub Bot commented on FLINK-8714:
---------------------------------------
GitHub user michalklempa opened a pull request:
https://github.com/apache/flink/pull/5536
[FLINK-8714][Documentation] Added either charsetName) or "utf-8" value in
examples of readTextFile
## What is the purpose of the change
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. "
*(For example: This pull request makes task deployment go through the blob
server, rather than through RPC. That way we avoid re-transferring them on each
deployment (during recovery).)*
Fixing this in documentation by providing charsetName in examples where the
API is described and "utf-8" as second argument in programming examples. This
should help others not to forget about the need to specify a charset
programmatically, if they want to avoid non-deterministic behavior depending on
environment.
## Brief change log
## Verifying this change
This change is a trivial rework of documentation 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
- If yes, how is the feature documented? not applicable
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/michalklempa/flink
FLINK-8714_readTextFile_charset_version
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/5536.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 #5536
----
commit 221684da5b564b21c1e0cc99e823c18939c0ca91
Author: Michal Klempa <michal.klempa@...>
Date: 2018-02-20T13:50:30Z
FLINK-8714 added either env.readTextFile(pathToFile, charsetName) where the
API is described or readTextFile(path/to/file, utf-8) where API is shown as
example
----
> 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
>
> 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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