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https://issues.apache.org/jira/browse/HDFS-3510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401765#comment-13401765
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Suresh Srinivas commented on HDFS-3510:
---------------------------------------
Finally took some time to review the tests as well. Here are some comments:
# TestNamenodeRecovery
#* Since you have just modified the tests, could you please add some javadoc to
EditLogTestSetup class. Also please add javadoc to newly added class
EltsTestOpcodesAfterPadding.
#* you may want to move adding delete operation to a method, to avoid code
duplication.
#* very minor - if padding length is zero, you may want to just return from
#padEditLog()
# TestEditlogFileOutputStream
#* Can you please add some javadoc to the class.
#* testRawWrites() - you can move the code that performs setReadyToFlusy(),
elos.flushAndSync() and length check to a method to avoid repeating the same
code
#* You do not need try finally. @Before method deleted the file.
> Improve FSEditLog pre-allocation
> --------------------------------
>
> Key: HDFS-3510
> URL: https://issues.apache.org/jira/browse/HDFS-3510
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 1.0.0, 2.0.0-alpha
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Fix For: 1.0.0, 2.0.1-alpha
>
> Attachments: HDFS-3510-b1.001.patch, HDFS-3510-b1.002.patch,
> HDFS-3510.001.patch, HDFS-3510.003.patch, HDFS-3510.004.patch,
> HDFS-3510.004.patch, HDFS-3510.006.patch, HDFS-3510.007.patch,
> HDFS-3510.008.patch, HDFS-3510.009.patch, HDFS-3510.010.patch
>
>
> It is good to avoid running out of space in the middle of writing a batch of
> edits, because when it happens, we often get partial edits at the end of the
> log.
> Edit log preallocation can solve this problem (see HADOOP-2330 for a full
> description of edit log preallocation).
> The current pre-allocation code was introduced for performance reasons, not
> for preventing partial edits. As a consequence, we sometimes do a write
> without using pre-allocation. We should change the pre-allocation code so
> that it always preallocates at least enough space before writing out the
> edits.
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