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https://issues.apache.org/jira/browse/HADOOP-19389?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17914189#comment-17914189
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ASF GitHub Bot commented on HADOOP-19389:
-----------------------------------------
cnauroth commented on code in PR #7291:
URL: https://github.com/apache/hadoop/pull/7291#discussion_r1920495312
##########
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestTextCommand.java:
##########
@@ -67,39 +75,194 @@ public void testDisplayForAvroFiles() throws Exception {
assertEquals(expectedOutput, output);
}
+ @Test
+ public void testEmptyAvroFile() throws Exception {
Review Comment:
I'm unclear about bringing this into a contract test. These tests are
covering semantics very specific to `hadoop fs -text`. The expectation is that
the command can decode Avro and sequence files and print them in JSON/text
representation. At the `FileSystem` layer, it would just be returning the raw
bytes. Existing contract tests cover "input bytes == output bytes". If
hdfs/s3a/azure/gcs get that part right, then the `hadoop fs -text` behavior
falls into place regardless of the FS.
However, maybe something we can do is expand contract coverage of reads in a
more generic way. For example, we could cover things like the bad argument
checks and "same data returned from read() vs. read(byte[]...)` during
`AbstractContractOpenTest`. Maybe some updates to the `FSDataInputStream`
specification docs too.
I'd recommend driving all this in a separate patch though.
> Optimize shell -text command I/O with multi-byte read.
> ------------------------------------------------------
>
> Key: HADOOP-19389
> URL: https://issues.apache.org/jira/browse/HADOOP-19389
> Project: Hadoop Common
> Issue Type: Improvement
> Components: command, fs, fs/azure, fs/gcs, fs/s3
> Affects Versions: 3.4.1
> Reporter: Chris Nauroth
> Assignee: Chris Nauroth
> Priority: Minor
> Labels: pull-request-available
>
> {{hadoop fs -text}} reads Avro files and sequence files by internally
> wrapping the stream in
> [{{AvroFileInputStream}}|https://github.com/apache/hadoop/blob/rel/release-3.4.1/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/Display.java#L270]
> or
> [{{TextRecordInputStream}}|https://github.com/apache/hadoop/blob/rel/release-3.4.1/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/Display.java#L217].
> These classes implement the required single-byte
> [{{read()}}|https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/InputStream.html#read()],
> but not the optional multi-byte buffered [{{read(byte[], int,
> int)}}|https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/InputStream.html#read(byte%5B%5D,int,int)].
> The default implementation in the JDK is a [loop over single-byte
> read|https://github.com/openjdk/jdk11u-dev/blob/a47c72fad455bfdf9053cb8e94c99e73965ab50d/src/java.base/share/classes/java/io/InputStream.java#L280],
> which causes sub-optimal I/O and method call overhead. We can optimize this
> by overriding the multi-byte read method.
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