Johannes Alberti created HIVE-17363:
---------------------------------------
Summary: Metrics output JSON_FILE issues with
{hive.service.metrics.file.location} not being renamed as expected
Key: HIVE-17363
URL: https://issues.apache.org/jira/browse/HIVE-17363
Project: Hive
Issue Type: Bug
Components: Configuration, Logging
Affects Versions: 2.1.1
Environment: CentOS 6.5/Hadoop 2.7.3/Java 7
Reporter: Johannes Alberti
Due to a patch introduced with HIVE-13705, the target output json file
(report.json) is not replace properly, only report.json.tmp is continuously
updated.
The local filesystem
(https://github.com/apache/hive/blob/branch-2.1/common/src/java/org/apache/hadoop/hive/common/metrics/metrics2/CodahaleMetrics.java#L428)
at the time of output is an instanceof ProxyLocalFileSystem
(https://github.com/apache/hive/blob/branch-2.1/ql/src/java/org/apache/hadoop/hive/ql/io/ProxyLocalFileSystem.java)
which overrides the rename method of the Hadoop LocalFileSystem.
The Hadooo LocalFileSystem delegates rename() to the JVM which delegates
rename() to the OS ...
http://pubs.opengroup.org/onlinepubs/9699919799/functions/rename.html.
The POSIX rename behavior is what the JSON_FILE output handler really wants
here, I assume, as it supposedly ensures that a reader thread at no time ends
up with no file, which in the deprecated Haddop FileSystem ... rename(src, dst,
options) method could occur.
No simple patch seems obvious, unless the JSON_FILE output handler would be
leveraging the JVM FileSystem in case a local filesystem for the output is
configured. Delegating to the Hadoop original LocalFilesystem seems not safe,
if we can assume that at one point in the future, Hadoop will align
LocalFileSystem and DFS behavior as requested originally in HDFS-10385.
Comments appreciated, I'm inclined to rip out the Hadoop LocalFileSystem here
and replace it with the JVM original.
Hive master seems to still have the same issue, at least no obvious code
changes are observed, despite some metrics refactoring
(https://github.com/apache/hive/blob/master/common/src/java/org/apache/hadoop/hive/common/metrics/metrics2/JsonFileMetricsReporter.java#L116)
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
