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Posted to dev@parquet.apache.org by "Julien Le Dem (JIRA)" <ji...@apache.org> on 2016/06/30 16:52:10 UTC
[jira] [Updated] (PARQUET-642) Improve performance of ByteBuffer
based read / write paths
[ https://issues.apache.org/jira/browse/PARQUET-642?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Julien Le Dem updated PARQUET-642:
----------------------------------
Assignee: Piyush Narang
> Improve performance of ByteBuffer based read / write paths
> ----------------------------------------------------------
>
> Key: PARQUET-642
> URL: https://issues.apache.org/jira/browse/PARQUET-642
> Project: Parquet
> Issue Type: Bug
> Reporter: Piyush Narang
> Assignee: Piyush Narang
> Fix For: 1.9.0
>
>
> While trying out the newest Parquet version, we noticed that the changes to start using ByteBuffers: https://github.com/apache/parquet-mr/commit/6b605a4ea05b66e1a6bf843353abcb4834a4ced8 and https://github.com/apache/parquet-mr/commit/6b24a1d1b5e2792a7821ad172a45e38d2b04f9b8 (mostly avro but a couple of ByteBuffer changes) caused our jobs to slow down a bit.
> Read overhead: 4-6% (in MB_Millis)
> Write overhead: 6-10% (MB_Millis).
> Seems like this seems to be due to the encoding / decoding of Strings in the Binary class (https://github.com/apache/parquet-mr/blob/master/parquet-column/src/main/java/org/apache/parquet/io/api/Binary.java) - toStringUsingUTF8() - for reads
> encodeUTF8() - for writes
> In those methods we're using the nio Charsets for encode / decode:
> {code}
> private static ByteBuffer encodeUTF8(CharSequence value) {
> try {
> return ENCODER.get().encode(CharBuffer.wrap(value));
> } catch (CharacterCodingException e) {
> throw new ParquetEncodingException("UTF-8 not supported.", e);
> }
> }
> }
> ...
> @Override
> public String toStringUsingUTF8() {
> int limit = value.limit();
> value.limit(offset+length);
> int position = value.position();
> value.position(offset);
> // no corresponding interface to read a subset of a buffer, would have to slice it
> // which creates another ByteBuffer object or do what is done here to adjust the
> // limit/offset and set them back after
> String ret = UTF8.decode(value).toString();
> value.limit(limit);
> value.position(position);
> return ret;
> }
> {code}
> Tried out some micro / macro benchmarks and it seems like switching those out to using the String class for the encoding / decoding improves performance:
> {code}
> @Override
> public String toStringUsingUTF8() {
> String ret;
> if (value.hasArray()) {
> try {
> ret = new String(value.array(), value.arrayOffset() + offset, length, "UTF-8");
> } catch (UnsupportedEncodingException e) {
> throw new ParquetDecodingException("UTF-8 not supported");
> }
> } else {
> int limit = value.limit();
> value.limit(offset+length);
> int position = value.position();
> value.position(offset);
> // no corresponding interface to read a subset of a buffer, would have to slice it
> // which creates another ByteBuffer object or do what is done here to adjust the
> // limit/offset and set them back after
> ret = UTF8.decode(value).toString();
> value.limit(limit);
> value.position(position);
> }
> return ret;
> }
> ...
> private static ByteBuffer encodeUTF8(String value) {
> try {
> return ByteBuffer.wrap(value.getBytes("UTF-8"));
> } catch (UnsupportedEncodingException e) {
> throw new ParquetEncodingException("UTF-8 not supported.", e);
> }
> }
> {code}
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