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https://issues.apache.org/jira/browse/HDFS-14820?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16926304#comment-16926304
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Lisheng Sun edited comment on HDFS-14820 at 9/10/19 3:38 AM:
-------------------------------------------------------------

hi [~elgoiri]
{quote}What is the current default value? 8KB?
{quote}
as follow code, current default value is 8KB.
{code:java}
final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(
      peer.getOutputStream()));

public BufferedOutputStream(OutputStream out) {
    this(out, 8192);
}
{code}
i have updated buffer is 512B, taken a lot tests and the resut is ok. I can do 
the pressure test and  use the new buffer in our prodution environment later.
 i agree your suggestion,we can first make it configurable and make the default 
the old value.

Adjust the buffer according to user need.


was (Author: leosun08):
hi [~elgoiri]
{quote}What is the current default value? 8KB?
{quote}
as follow code, current default value is 8KB.
{code:java}
final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(
      peer.getOutputStream()));

public BufferedOutputStream(OutputStream out) {
    this(out, 8192);
}
{code}
i have updated buffer is 512B, taken a test and the resut is ok.
 i agree your suggestion,make it configurable and make the default the old 
value.

>  The default 8KB buffer of 
> BlockReaderRemote#newBlockReader#BufferedOutputStream is too big
> -------------------------------------------------------------------------------------------
>
>                 Key: HDFS-14820
>                 URL: https://issues.apache.org/jira/browse/HDFS-14820
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Lisheng Sun
>            Assignee: Lisheng Sun
>            Priority: Major
>         Attachments: HDFS-14820.001.patch
>
>
> this issue is similar to HDFS-14535.
> {code:java}
> public static BlockReader newBlockReader(String file,
>     ExtendedBlock block,
>     Token<BlockTokenIdentifier> blockToken,
>     long startOffset, long len,
>     boolean verifyChecksum,
>     String clientName,
>     Peer peer, DatanodeID datanodeID,
>     PeerCache peerCache,
>     CachingStrategy cachingStrategy,
>     int networkDistance) throws IOException {
>   // in and out will be closed when sock is closed (by the caller)
>   final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(
>       peer.getOutputStream()));
>   new Sender(out).readBlock(block, blockToken, clientName, startOffset, len,
>       verifyChecksum, cachingStrategy);
> }
> public BufferedOutputStream(OutputStream out) {
>     this(out, 8192);
> }
> {code}
> Sender#readBlock parameter( block,blockToken, clientName, startOffset, len, 
> verifyChecksum, cachingStrategy) could not use such a big buffer.
> So i think it should reduce BufferedOutputStream buffer.



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