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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* 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.test;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import org.apache.pig.PigRunner;
import org.apache.pig.PigServer;
import org.apache.pig.impl.PigContext;
import org.apache.pig.tools.pigstats.JobStats;
import org.apache.pig.tools.pigstats.PigStats;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import static org.junit.Assert.*;
/**
* This class tests whether the number of reducers is correctly set for queries
* involving a sample job. Note the sample job should use the actual #reducers
* of the following order-by or skew-join job to generate the partition file,
* and the challenge is that whether we can get the actual #reducer of the
* order-by/skew-join job in advance.
*/
@RunWith(JUnit4.class)
public class TestNumberOfReducers {
private static final String LOCAL_INPUT_FILE = "test/org/apache/pig/test/data/passwd";
private static final String HDFS_INPUT_FILE = "passwd";
private static final String OUTPUT_FILE = "output";
private static final String PIG_FILE = "test.pig";
static PigContext pc;
static PigServer pigServer;
private static MiniCluster cluster;
@BeforeClass
public static void setUpBeforeClass() throws Exception {
cluster = MiniCluster.buildCluster();
Util.copyFromLocalToCluster(cluster, LOCAL_INPUT_FILE, HDFS_INPUT_FILE);
}
@AfterClass
public static void oneTimeTearDown() throws Exception {
cluster.shutDown();
}
/**
* Specifying bytes_per_reducer, default_parallel and parallel, verifying
* whether it uses the actual #reducers as actual_parallel.
*
* Note the input file size is 555B.
*
*/
private void verifyOrderBy(int bytes_per_reducer, int default_parallel,
int parallel, int actual_parallel) throws IOException {
PrintWriter w = new PrintWriter(new FileWriter(PIG_FILE));
// the file is 555B
w.println("SET pig.exec.reducers.bytes.per.reducer " + bytes_per_reducer + ";");
w.println("SET default_parallel " + default_parallel + ";");
w.println("A = load '" + HDFS_INPUT_FILE + "';");
w.print("B = order A by $0 ");
if (parallel > 0)
w.print("parallel " + parallel);
w.println(";");
w.println("store B into '" + OUTPUT_FILE + "';");
w.close();
doTest(bytes_per_reducer, default_parallel, parallel, actual_parallel);
}
/**
* Specifying bytes_per_reducer, default_parallel and parallel, verifying
* whether it uses the actual #reducers as actual_parallel.
*
* Note the input file size is 555B.
*
*/
private void verifySkewJoin(int bytes_per_reducer, int default_parallel,
int parallel, int actual_parallel) throws IOException {
PrintWriter w = new PrintWriter(new FileWriter(PIG_FILE));
// the file is 555B
w.println("SET pig.exec.reducers.bytes.per.reducer " + bytes_per_reducer + ";");
w.println("SET default_parallel " + default_parallel + ";");
w.println("A1 = load '" + HDFS_INPUT_FILE + "';");
w.println("A2 = load '" + HDFS_INPUT_FILE + "';");
w.print("B = join A1 by $0, A2 by $0 using 'skewed' ");
if (parallel > 0)
w.print("parallel " + parallel);
w.println(";");
w.println("store B into '" + OUTPUT_FILE + "';");
w.close();
doTest(bytes_per_reducer, default_parallel, parallel, actual_parallel);
}
private void doTest(double bytes_per_reducer, int default_parallel,
int parallel, int actual_parallel) throws IOException {
try {
String[] args = { PIG_FILE };
PigStats stats = PigRunner.run(args, null);
assertTrue(stats.isSuccessful());
// get the skew-join job stat
JobStats js = (JobStats) stats.getJobGraph().getSinks().get(0);
assertEquals(actual_parallel, js.getNumberReduces());
// estimation should only kick in if parallel and default_parallel are not set
long estimatedReducers = -1;
if (parallel < 1 && default_parallel < 1) {
double fileSize = (double)(new File("test/org/apache/pig/test/data/passwd").length());
int inputFiles = js.getInputs().size();
estimatedReducers = Math.min((long)Math.ceil(fileSize/(double)bytes_per_reducer) * inputFiles, 999);
}
Util.assertParallelValues(default_parallel, parallel, estimatedReducers,
actual_parallel, js.getInputs().get(0).getConf());
} catch (Exception e) {
assertNull("Exception thrown during verifySkewJoin", e);
} finally {
new File(PIG_FILE).delete();
Util.deleteFile(cluster, OUTPUT_FILE);
}
}
/**
* For 550B file and 300B per reducer, it estimates 2 #reducers.
* @throws Exception
*/
@Test
public void testOrderByEstimate() throws Exception{
verifyOrderBy(300, -1, -1, 2);
}
/**
* For two 550B files and 600B per reducer, it estimates 2 #reducers.
* @throws Exception
*/
@Test
public void testSkewJoinEstimate() throws Exception{
verifySkewJoin(600, -1, -1, 2);
}
/**
* Pig will estimate 2 reducers but we specify parallel 1, so it should use
* 1 reducer.
*
* @throws Exception
*/
@Test
public void testOrderByEstimate2Parallel1() throws Exception {
verifyOrderBy(300, -1, 1, 1);
}
/**
* Pig will estimate 2 reducers but we specify parallel 1, so it should use
* 1 reducer.
*
* @throws Exception
*/
@Test
public void testSkewJoinEstimate2Parallel1() throws Exception {
verifySkewJoin(600, -1, 1, 1);
}
/**
* Pig will estimate 2 reducers but we specify default parallel 1, so it
* should use 1 reducer.
*
* @throws Exception
*/
@Test
public void testOrderByEstimate2Default1() throws Exception {
verifyOrderBy(300, 1, -1, 1);
}
/**
* Pig will estimate 2 reducers but we specify default parallel 1, so it
* should use 1 reducer.
*
* @throws Exception
*/
@Test
public void testSkewJoinEstimate2Default1() throws Exception {
verifySkewJoin(600, 1, -1, 1);
}
/**
* Pig will estimate 2 reducers but we specify parallel 4, so it should use
* 4 reducer.
*
* TODO we need verify that the sample job generates 4 partitions instead of
* 2.
*
* @throws Exception
*/
@Test
public void testOrderByEstimate2Parallel4() throws Exception {
verifyOrderBy(300, -1, 4, 4);
}
/**
* Pig will estimate 2 reducers but we specify parallel 4, so it should use
* 4 reducer.
*
* TODO we need verify that the sample job generates 4 partitions instead of
* 2.
*
* @throws Exception
*/
@Test
public void testSkewJoinEstimate2Parallel4() throws Exception {
verifySkewJoin(600, -1, 4, 4);
}
/**
* Pig will estimate 6 reducers but we specify default parallel 2, so it
* should use 2 reducer. Also, the sampler should generate 2 partitions,
* instead of 6, otherwise the next job will fail.
*
* @throws Exception
*/
@Test
public void testOrderByEstimate6Default2() throws Exception {
verifyOrderBy(100, 2, -1, 2);
}
/**
* Pig will estimate 6 reducers but we specify default parallel 2, so it
* should use 2 reducer. Also, the sampler should generate 2 partitions,
* instead of 6, otherwise the next job will fail.
*
* @throws Exception
*/
@Test
public void testSkewJoinEstimate6Default2() throws Exception {
verifySkewJoin(200, 2, -1, 2);
}
}