org.apache.pig.data.SizeUtil Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.pig.data;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.pig.classification.InterfaceAudience;
import org.apache.pig.classification.InterfaceStability;
/**
* Utility functions for estimating size of objects of pig types
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class SizeUtil {
private static final int MAP_MEM_PER_ENTRY = 32 + 120;
public static long getPigObjMemSize(Object o) {
// 12 is added to each to account for the object overhead and the
// pointer in the tuple.
switch (DataType.findType(o)) {
case DataType.BYTEARRAY: {
byte[] bytes = ((DataByteArray) o).get();
// bytearray size including rounding to 8 bytes
long byte_array_sz = roundToEight(bytes.length + 12);
return byte_array_sz + 16 /* 16 is additional size of DataByteArray */;
}
case DataType.CHARARRAY: {
String s = (String) o;
// See PIG-1443 for a reference for this formula
return roundToEight((s.length() * 2) + 38);
}
case DataType.TUPLE: {
Tuple t = (Tuple) o;
return t.getMemorySize();
}
case DataType.BAG: {
DataBag b = (DataBag) o;
return b.getMemorySize();
}
case DataType.INTEGER:
return 4 + 8 + 4/* +4 to round to 8 bytes */;
case DataType.LONG:
return 8 + 8;
case DataType.DATETIME:
return 8 + 2 + 8 + 6 /* one long (8) + one short (2) + 6 to round to 8 bytes */;
case DataType.MAP: {
@SuppressWarnings("unchecked")
Map m = (Map) o;
Iterator> i = m.entrySet().iterator();
long sum = 0;
while (i.hasNext()) {
Entry entry = i.next();
sum += getMapEntrySize(entry.getKey(), entry.getValue());
}
return sum;
}
case DataType.FLOAT:
return 4 + 8 + 4/* +4 to round to 8 bytes */;
case DataType.DOUBLE:
return 8 + 8;
case DataType.BOOLEAN:
// boolean takes 1 byte , +7 to round it to 8
return 1 + 8 + 7;
case DataType.NULL:
return 0;
default:
// ??
return 12;
}
}
public static long getMapEntrySize(Object key, Object value) {
// based on experiments on 32 bit Java HotSpot VM
// size of map with 0 entries is 120 bytes
// each additional entry have around 24 bytes overhead at
// small number of entries. At larger number of entries, the
// overhead is around 32 bytes, probably because of the expanded
// data structures in anticapation of more entries being added
return getPigObjMemSize(key) + getPigObjMemSize(value)
+ MAP_MEM_PER_ENTRY;
}
/**
* Memory size of objects are rounded to multiple of 8 bytes
*
* @param i
* @return i rounded to a equal of higher multiple of 8
*/
public static long roundToEight(long i) {
return 8 * ((i + 7) / 8); // integer division rounds the result down
}
}