[jira] [Issue Comment Edited] (CASSANDRA-2252) arena allocation for memtables

[Yang Yang (JIRA)]

    [ 
https://issues.apache.org/jira/browse/CASSANDRA-2252?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13092600#comment-13092600
 ] 

Yang Yang edited comment on CASSANDRA-2252 at 8/29/11 2:33 AM:
---------------------------------------------------------------

"if it's a memtable-related operation" ---- CounterContext.allocate produces a 
ByteBuffer , some of which goes into CounterColumn, hence Memtable, it seems.

for example:

CounterMutation.computeShardMerger() ==> CounterColumn.computeOldShardMerger()
===> ByteBuffer contextManager.computeOldShardMerger {
      ......
       ContextState merger = ContextState.allocate(2, nbDelta, 
HeapAllocator.instance);
         ....
     return merger.context;
}

the "merger.context" is a ByteBuffer that is inserted into CounterColumn by 
CounterColumn.computeOldShardMerger()



Thanks
Yang


      was (Author: yangyangyyy):
    "if it's a memtable-related operation" ---- aren't the CounterContext's 
finally inserted into the CounterColumns, hence the Memtable too ?

for example:

CounterMutation.computeShardMerger() ==> CounterColumn.computeOldShardMerger()
===> ByteBuffer contextManager.computeOldShardMerger {
      ......
       ContextState merger = ContextState.allocate(2, nbDelta, 
HeapAllocator.instance);
         ....
     return merger.context;
}

the "merger.context" is a ByteBuffer that is inserted into CounterColumn by 
CounterColumn.computeOldShardMerger()



Thanks
Yang

  
> arena allocation for memtables
> ------------------------------
>
>                 Key: CASSANDRA-2252
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2252
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>             Fix For: 1.0
>
>         Attachments: 0001-add-MemtableAllocator.txt, 
> 0002-add-off-heap-MemtableAllocator-support.txt, 2252-v3.txt, 2252-v4.txt, 
> merged-2252.tgz
>
>
> The memtable design practically actively fights Java's GC design.  Todd 
> Lipcon gave a good explanation over on HBASE-3455.

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