Anoop Sam John created HBASE-15180:
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Summary: Reduce garbage created while reading Cells from Codec
Decoder
Key: HBASE-15180
URL: https://issues.apache.org/jira/browse/HBASE-15180
Project: HBase
Issue Type: Sub-task
Reporter: Anoop Sam John
Assignee: Anoop Sam John
In KeyValueDecoder#parseCell (Default Codec decoder) we use
KeyValueUtil#iscreate to read cells from the InputStream. Here we 1st create a
byte[] of length 4 and read the cell length and then an array of Cell's length
and read in cell bytes into it and create a KV.
Actually in server we read the reqs into a byte[] and CellScanner is created on
top of a ByteArrayInputStream on top of this. By default in write path, we have
MSLAB usage ON. So while adding Cells to memstore, we will copy the Cell bytes
to MSLAB memory chunks (default 2 MB size) and recreate Cells over that bytes.
So there is no issue if we create Cells over the RPC read byte[] directly here
in Decoder. No need for 2 byte[] creation and copy for every Cell in request.
My plan is to make a Cell aware ByteArrayInputStream which can read Cells
directly from it.
Same Codec path is used in client side also. There better we can avoid this
direct Cell create and continue to do the copy to smaller byte[]s path. Plan
to introduce some thing like a CodecContext associated with every Codec
instance which can say the server/client context.
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