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https://issues.apache.org/jira/browse/HBASE-16205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15390517#comment-15390517
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Yu Li commented on HBASE-16205:
-------------------------------
Let me try to explain: in {{upsert()}} we have below code now:
{code}
long addedSize = internalAdd(cell, false);
...
while (it.hasNext()) {
Cell cur = it.next();
if (cell == cur) {
// ignore the one just put in
continue;
}
...
{code}
So if we call deepCopy inside {{internalAdd}} like we did in v2 patch, the cell
put into the cellset will be a different object than {{cell}} here in
{{upsert()}}, and the {{if (cell == cur)}} check will return false, which
causes the problem. I think this is the reason we have to deepCopy in different
places.
And patch v3 lgtm, +1 btw :-)
> When Cells are not copied to MSLAB, deep clone it while adding to Memstore
> --------------------------------------------------------------------------
>
> Key: HBASE-16205
> URL: https://issues.apache.org/jira/browse/HBASE-16205
> Project: HBase
> Issue Type: Sub-task
> Components: regionserver
> Affects Versions: 2.0.0
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HBASE-16205.patch, HBASE-16205_V2.patch,
> HBASE-16205_V3.patch, HBASE-16205_V3.patch
>
>
> This is imp after HBASE-15180 optimization. After that we the cells flowing
> in write path will be backed by the same byte[] where the RPC read the
> request into. By default we have MSLAB On and so we have a copy operation
> while adding Cells to memstore. This copy might not be there if
> 1. MSLAB is turned OFF
> 2. Cell size is more than a configurable max size. This defaults to 256 KB
> 3. If the operation is Append/Increment.
> In such cases, we should just clone the Cell into a new byte[] and then add
> to memstore. Or else we keep referring to the bigger byte[] chunk for longer
> time.
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