Rohini Palaniswamy created PIG-5288:
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Summary: Improve performance of PigTextRawBytesComparator
Key: PIG-5288
URL: https://issues.apache.org/jira/browse/PIG-5288
Project: Pig
Issue Type: Improvement
Reporter: Rohini Palaniswamy
Assignee: Rohini Palaniswamy
Fix For: 0.18.0
Came across this stacktrace for a group by when investigating a different
performance issue.
{code}
"TezChild" #22 daemon prio=5 os_prio=0 tid=0x00007fa935495000 nid=0x7c3e
runnable [0x00007fa91d354000]
java.lang.Thread.State: RUNNABLE
at sun.nio.cs.UTF_8$Decoder.decodeLoop(UTF_8.java:412)
at java.nio.charset.CharsetDecoder.decode(CharsetDecoder.java:579)
at java.nio.charset.CharsetDecoder.decode(CharsetDecoder.java:802)
at org.apache.hadoop.io.Text.decode(Text.java:412)
at org.apache.hadoop.io.Text.decode(Text.java:389)
at org.apache.hadoop.io.Text.toString(Text.java:280)
at
org.apache.pig.impl.io.NullableText.getValueAsPigType(NullableText.java:46)
at
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigTextRawComparator.compare(PigTextRawComparator.java:95)
at
org.apache.tez.runtime.library.common.ValuesIterator.readNextKey(ValuesIterator.java:188)
at
org.apache.tez.runtime.library.common.ValuesIterator.access$300(ValuesIterator.java:47)
at
org.apache.tez.runtime.library.common.ValuesIterator$1$1.next(ValuesIterator.java:143)
at
org.apache.pig.backend.hadoop.executionengine.tez.plan.operator.POShuffleTezLoad.getNextTuple(POShuffleTezLoad.java:218)
{code}
Conversion to String and comparing is a wastage (result of extending from
PigTextRawBytesComparator which is used in sorting).
PigCharArrayWritableComparator which is the equivalent used in mapreduce does
not. It directly compares it as a Text.
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