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https://issues.apache.org/jira/browse/HBASE-14873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15032880#comment-15032880
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Hiroshi Ikeda commented on HBASE-14873:
---------------------------------------
{quote}
This might have grown to bigger size but then also we will recreate DBB when
the original one (got from pool) was DBB
{quote}
Ops, my bad. I jumped a wrong conclusion. Now,
{quote}
The issue with BufferChain#getBytes () can fixed with simple fix no? Why this
much changes? Am I missing some thing?
{quote}
I agree. My patch involves improvement to reuse all direct buffers, which is
not appropriate to just fix the bug. I was too nervous of throwing them away,
and I'll create a new patch.
{quote}
bq. The purpose of BoudnedByteBufferPool becomes vague.
How is it vague [~ikeda]?
{quote}
I mean, we should manage direct buffers and non-direct buffers in different
ways, which requires us to write codes in different ways, and I don't find a
place to use BoundedByteBufferPool with switching direct/non-direct buffers
later.
> Problems around BoundedByteBufferPool providing direct buffers
> --------------------------------------------------------------
>
> Key: HBASE-14873
> URL: https://issues.apache.org/jira/browse/HBASE-14873
> Project: HBase
> Issue Type: Bug
> Reporter: Hiroshi Ikeda
> Assignee: Hiroshi Ikeda
> Fix For: 2.0.0
>
> Attachments: HBASE-14873.patch, HBASE-14873.patch, HBASE-14873.patch
>
>
> HBASE-13819 made BoundedByteBufferPool provide direct buffers.
> See RpcServer.java:
> {code}
> ...
> class Call implements RpcCallContext {
> protected synchronized void setResponse(...) {
> ...
> this.cellBlock = ipcUtil.buildCellBlock(..., reservoir);
> ...
> bc = new BufferChain(..., this.cellBlock);
> if (connection.useWrap) {
> bc = wrapWithSasl(bc);
> }
> ...
> private BufferChain wrapWithSasl(BufferChain bc) throws IOException {
> ...
> byte[] responseBytes = bc.getBytes();
> ...
> {code}
> {{cellBlock}} is expected to be a direct buffer retrieved from {{reservoir}}
> (but not always), and {{bc}} may be composed of both direct and non-direct
> buffers.
> And then, see BufferChain.java:
> {code}
> byte [] getBytes() {
> ...
> for (ByteBuffer bb: this.buffers) {
> System.arraycopy(bb.array(), ...);
> {code}
> A direct buffer doesn't give its array, and will throw
> UnsupportedOperationException.
> Another problem; {{cellBlock}} is allowed to be a non-direct buffer, and
> after use it will be put to {{reservoir}}, mixing direct and non-direct
> buffers in the pool.
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