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https://issues.apache.org/jira/browse/HDFS-15493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17168917#comment-17168917
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Stephen O'Donnell commented on HDFS-15493:
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I tested with the 004 patch:
* Parallel Load on + this feature on - 209 / 207 seconds
* Parallel Load on + this feature off - 225 / 228 seconds
* Parallel Load off + this feature off = 370 / 408 seconds
* Parallel Load off + this feature on = 325 / 341 seconds
This new patch improves things significantly, so I think we should go forward
with this technique.
I think we should create a new patch where the feature cannot be enabled /
disabled - just have it always on, as I cannot think of a good reason someone
should turn it off, and it will make the code simpler if we just remove the
switch. What do you think?
> Update block map and name cache in parallel while loading fsimage.
> ------------------------------------------------------------------
>
> Key: HDFS-15493
> URL: https://issues.apache.org/jira/browse/HDFS-15493
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Chengwei Wang
> Priority: Major
> Attachments: HDFS-15493.001.patch, HDFS-15493.002.patch,
> HDFS-15493.003.patch, HDFS-15493.004.patch, fsimage-loading.log
>
>
> While loading INodeDirectorySection of fsimage, it will update name cache and
> block map after added inode file to inode directory. It would reduce time
> cost of fsimage loading to enable these steps run in parallel.
> In our test case, with patch HDFS-13694 and HDFS-14617, the time cost to load
> fsimage (220M files & 240M blocks) is 470s, with this patch , the time cost
> reduc to 410s.
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