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Posted to issues@hbase.apache.org by "BELUGA BEHR (JIRA)" <ji...@apache.org> on 2018/03/14 15:14:38 UTC
[jira] [Updated] (HBASE-20197) Review of
ByteBufferWriterOutputStream.java
[ https://issues.apache.org/jira/browse/HBASE-20197?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
BELUGA BEHR updated HBASE-20197:
--------------------------------
Attachment: HBASE-20197.1.patch
> 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: 2.0.0, 1.4.2
> Reporter: BELUGA BEHR
> Priority: Minor
> 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.
>
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