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https://issues.apache.org/jira/browse/HDFS-17364?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17824416#comment-17824416
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ASF GitHub Bot commented on HDFS-17364:
---------------------------------------
bbeaudreault commented on code in PR #6514:
URL: https://github.com/apache/hadoop/pull/6514#discussion_r1516181907
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java:
##########
@@ -3159,6 +3165,21 @@ private void initThreadsNumForStripedReads(int
numThreads) {
}
}
+ private void initBufferPoolForStripedReads(boolean useWeakReference) {
+ if (STRIPED_READ_BUFFER_POOL != null) {
+ return;
+ }
+ synchronized (DFSClient.class) {
Review Comment:
@Hexiaoqiao thanks for review. For this block, it's sort of modeled after
other examples in DFSClient, such [as initializing the striped read thread
pool](https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java#L3150).
I think the idea is that DFSClient could easily be used in multiple threads,
so we want to avoid double initializing the shared resource.
> Use WeakReferencedElasticByteBufferPool in DFSStripedInputStream
> ----------------------------------------------------------------
>
> Key: HDFS-17364
> URL: https://issues.apache.org/jira/browse/HDFS-17364
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Bryan Beaudreault
> Priority: Major
> Labels: pull-request-available
>
> DFSStripedInputStream uses ElasticByteBufferPool to allocate byte buffers for
> the "curStripeBuf". This is used for non-positional (stateful) reads and is
> allocated with a size of numDataBlocks * cellSize. For RS-6-3-1024k, that
> means each DFSStripedInputStream could allocate a 6mb buffer. When the IS is
> finished, the buffer is put back in the pool. Over time and with spikes of
> concurrent reads, the pool grows and most of the buffers sit there unused.
>
> WeakReferencedElasticByteBufferPool was introduced HADOOP-18105 and mitigates
> this issue because the excess buffers can be GC'd once they are no longer
> needed. We should use this same pool in DFSStripedInputStream
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