BELUGA BEHR created HBASE-20197:
-----------------------------------
Summary: Review of ByteBufferWriterOutputStream.java
Key: HBASE-20197
URL: https://issues.apache.org/jira/browse/HBASE-20197
Project: HBase
Issue Type: Improvement
Components: hbase
Affects Versions: 1.4.2, 2.0.0
Reporter: BELUGA BEHR
Attachments: HBASE-20197.1.patch
In looking at this class, two things caught my eye.
# Default buffer size of 4K
# Re-sizing of buffer on demand
Java's {{BufferedOutputStream}} uses an internal buffer size of 8K on modern
JVMs. This is due to various bench-marking that showed optimal performance at
this level.
The Re-sizing buffer looks a bit "unsafe":
{code:java}
public void write(ByteBuffer b, int off, int len) throws IOException {
byte[] buf = null;
if (len > TEMP_BUF_LENGTH) {
buf = new byte[len];
} else {
if (this.tempBuf == null) {
this.tempBuf = new byte[TEMP_BUF_LENGTH];
}
buf = this.tempBuf;
}
...
}
{code}
If this method gets one call with a 'len' of 4000, then 4001, then 4002, then
4003, etc. then the 'tempBuf' will be re-created many times. Also, it seems
unsafe to create a buffer as large as the 'len' input. This could
theoretically lead to an internal buffer of 2GB for each instance of this class.
I propose:
# Increase the default buffer size to 8K
# Create the buffer once and chunk the output instead of loading data into a
single array and writing it to the output stream.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
