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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14873) Problems around BoundedByteBufferPool providing direct buffers
Date Mon, 30 Nov 2015 19:11:11 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15032275#comment-15032275
] 

stack commented on HBASE-14873:
-------------------------------

bq. The purpose of BoudnedByteBufferPool becomes vague. Is it better to prepare an independent
pool for socket channels?

How is it vague [~ikeda]? We need pool of bytebuffers. Having the pool offheap seems to make
for savings at no slowdown (other than initial allocation being slower) especially when we
are doing copy from BB to socket so why not just have BBP be always DBB?

> 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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