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https://issues.apache.org/jira/browse/HDFS-7859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16152584#comment-16152584
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Kai Zheng commented on HDFS-7859:
---------------------------------
Thanks [~Sammi] for the update!
Some comments so far:
1. Did you notice some failure or error for the current behavior of
{{ElasticByteBufferPool->getBuffer(boolean direct, int length)}}? It looks
reasonable to me that it can return a ByteBuffer of larger capacity than
required; it can the caller's responsibility to use it well. Anyway, it's not
relevant to this issue, so would you please handle it separately? Thanks.
{code}
---
a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/ElasticByteBufferPool.java
+++
b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/ElasticByteBufferPool.java
@@ -96,7 +96,8 @@ public synchronized ByteBuffer getBuffer(boolean direct, int
length) {
ByteBuffer.allocate(length);
}
tree.remove(entry.getKey());
- return entry.getValue();
+ // The reused ByteBuffer may have more capacity than required(length)
+ return (ByteBuffer) entry.getValue().limit(length);
}
{code}
2. Similarly, please also do the large portion of changes in
{{CodecRegistry/CodecUtil}} separately. It's really not very relevant to this.
3. Again, in {{DFSStripedOutputStream}} please do it elsewhere (better with
some test), I wish this could focus on the NN side changes when possible.
{code}
private void clear() {
for (int i = 0; i< numAllBlocks; i++) {
buffers[i].clear();
+ buffers[i] = (ByteBuffer) buffers[i].limit(cellSize);
}
}
{code}
> Erasure Coding: Persist erasure coding policies in NameNode
> -----------------------------------------------------------
>
> Key: HDFS-7859
> URL: https://issues.apache.org/jira/browse/HDFS-7859
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: SammiChen
> Labels: hdfs-ec-3.0-must-do
> Attachments: HDFS-7859.001.patch, HDFS-7859.002.patch,
> HDFS-7859.004.patch, HDFS-7859.005.patch, HDFS-7859.006.patch,
> HDFS-7859.007.patch, HDFS-7859.008.patch, HDFS-7859.009.patch,
> HDFS-7859.010.patch, HDFS-7859.011.patch, HDFS-7859.012.patch,
> HDFS-7859-HDFS-7285.002.patch, HDFS-7859-HDFS-7285.002.patch,
> HDFS-7859-HDFS-7285.003.patch
>
>
> In meetup discussion with [~zhz] and [~jingzhao], it's suggested that we
> persist EC schemas in NameNode centrally and reliably, so that EC zones can
> reference them by name efficiently.
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