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https://issues.apache.org/jira/browse/HDFS-7276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14187317#comment-14187317
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Tsz Wo Nicholas Sze commented on HDFS-7276:
-------------------------------------------
The percentage differences are shown in the performance test
{noformat}
arrayLength=65536, nThreads=512, nAllocations=32768, maxArrays=1024
NewByteArrayWithoutLimit: 3439, 3394, 3497, 3459, 3442, avg= 3.446s
NewByteArrayWithLimit: 3448, 3563, 3552, 3492, 3509, avg= 3.513s (
1.93%)
UsingByteArrayManager: 3357, 3369, 3327, 3345, 3324, avg= 3.344s (
-2.95%) ( -4.79%)
{noformat}
The time elapsed for UsingByteArrayManager is 2.95% and 4.79% less than
NewByteArrayWithoutLimit and NewByteArrayWithLimit, respectively.
> Limit the number of byte arrays used by DFSOutputStream
> -------------------------------------------------------
>
> Key: HDFS-7276
> URL: https://issues.apache.org/jira/browse/HDFS-7276
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Tsz Wo Nicholas Sze
> Attachments: h7276_20141021.patch, h7276_20141022.patch,
> h7276_20141023.patch, h7276_20141024.patch, h7276_20141027.patch,
> h7276_20141027b.patch, h7276_20141028.patch
>
>
> When there are a lot of DFSOutputStream's writing concurrently, the number of
> outstanding packets could be large. The byte arrays created by those packets
> could occupy a lot of memory.
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