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Flume >> mail # dev >> Review Request: FLUME-1660 Close "idle" hdfs handles

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Re: Review Request: FLUME-1660 Close "idle" hdfs handles

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(Updated Nov. 14, 2012, 8 a.m.)
Review request for Flume and Mike Percy.

Added a unit test.

There's some commentary on a corner case in there... If you process an event just as the close is happening, what can happen is the following:
- process gets handle to the bucketwriter
- (in the timer thread)that bucketwriter times out, get closed and removed from map
- (in the sink runner/test thread)the bucketwriter has append called on it, opening up a new file with a single append to it
- a new bucketwriter is created for following events, which will be writing to a different location.

it results in an extra file with a single append, so while not disastrous it's not exactly a great situation(though likely very rare)

The only way I can see to fix it is to introduce a synchronization block around the map removal in the callback and the map.get/map.insert in the process() call. The synchronization block was one of the things that we had been wanting to avoid for this alternate method for the implementation...

Added lastWrite to BucketWriter to verify when it was last updated

Added a thread to HDFSEventSink which verifies the last update of each active bucketWriter and closes them after the configurable timeout hdfs.closeIdleTimeout has passed.
This addresses bug FLUME-1660.
Diffs (updated)

  flume-ng-doc/sphinx/FlumeUserGuide.rst c1303e0
  flume-ng-sinks/flume-hdfs-sink/src/main/java/org/apache/flume/sink/hdfs/BucketWriter.java 9f2c763
  flume-ng-sinks/flume-hdfs-sink/src/main/java/org/apache/flume/sink/hdfs/HDFSEventSink.java e369604
  flume-ng-sinks/flume-hdfs-sink/src/test/java/org/apache/flume/sink/hdfs/TestBucketWriter.java 6a8072e
  flume-ng-sinks/flume-hdfs-sink/src/test/java/org/apache/flume/sink/hdfs/TestHDFSEventSink.java fee4c8b

Diff: https://reviews.apache.org/r/7659/diff/

Local machine testing was performed and the correct closing of files was confirmed, as well as the correct behavior of the configuration setting including disabling the feature(by using the default value for hdfs.closeIdleTimeout of 0)
There is one unrelated test failure which I'm not sure of(if anyone knows what's causing this, please let me know)

Failed tests:   testInOut(org.apache.flume.test.agent.TestFileChannel): Expected FILE_ROLL sink's dir to have only 1 child, but found 0 children. expected:<1> but was:<0>

All other tests pass.

Juhani Connolly