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https://issues.apache.org/jira/browse/HDFS-7276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14192322#comment-14192322
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Tsz Wo Nicholas Sze commented on HDFS-7276:
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bq. Can't we simply create those 12 or so managers immediately, and avoid all
the "create a new manager if statistics say so" logic?
ByteArrayManager is a generic class. So it may not necessarily be 12.
{quote}
174 wait(1000);
Why does this wait have a timeout? There isn't anything that we're polling here.
... synchronized int recycle(byte[] array) {
...
notifyAll();
Shouldn't this simply be "notify"? There is no point in waking up all waiters,
because only one of them is going to get the buffer we're recycling.
{quote}
Both the wait time out and the notifyAll are for preventing deadlock. After
some thought, only one of them is needed. I choose to keep notifyAll since the
timeout value is hard to determine.
> 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, h7276_20141029.patch,
> h7276_20141029b.patch, h7276_20141030.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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