Author: szetszwo
Date: Wed Jun 25 02:22:15 2014
New Revision: 1605239
URL: http://svn.apache.org/r1605239
Log:
HADOOP-10674. Improve PureJavaCrc32 performance and use java.util.zip.CRC32 for
Java 7 and above.
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFs.java
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipDecompressor.java
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/PureJavaCrc32.java
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestPureJavaCrc32.java
Modified: hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
--- hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt
(original)
+++ hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt Wed Jun
25 02:22:15 2014
@@ -472,6 +472,9 @@ Release 2.5.0 - UNRELEASED
HADOOP-10747. Support configurable retries on SASL connection failures in
RPC client. (cnauroth)
+ HADOOP-10674. Improve PureJavaCrc32 performance and use java.util.zip.CRC32
+ for Java 7 and above. (szetszwo)
+
OPTIMIZATIONS
BUG FIXES
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
(original)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java
Wed Jun 25 02:22:15 2014
@@ -18,7 +18,9 @@
package org.apache.hadoop.fs;
-import java.io.*;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
import java.nio.channels.ClosedChannelException;
import java.util.Arrays;
@@ -26,8 +28,8 @@ import org.apache.hadoop.classification.
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.permission.FsPermission;
+import org.apache.hadoop.util.DataChecksum;
import org.apache.hadoop.util.Progressable;
-import org.apache.hadoop.util.PureJavaCrc32;
/****************************************************************
* Abstract Checksumed FileSystem.
@@ -147,7 +149,7 @@ public abstract class ChecksumFileSystem
if (!Arrays.equals(version, CHECKSUM_VERSION))
throw new IOException("Not a checksum file: "+sumFile);
this.bytesPerSum = sums.readInt();
- set(fs.verifyChecksum, new PureJavaCrc32(), bytesPerSum, 4);
+ set(fs.verifyChecksum, DataChecksum.newCrc32(), bytesPerSum, 4);
} catch (FileNotFoundException e) { // quietly ignore
set(fs.verifyChecksum, null, 1, 0);
} catch (IOException e) { // loudly ignore
@@ -259,8 +261,7 @@ public abstract class ChecksumFileSystem
private Path file;
private long fileLen = -1L;
- FSDataBoundedInputStream(FileSystem fs, Path file, InputStream in)
- throws IOException {
+ FSDataBoundedInputStream(FileSystem fs, Path file, InputStream in) {
super(in);
this.fs = fs;
this.file = file;
@@ -379,7 +380,7 @@ public abstract class ChecksumFileSystem
long blockSize,
Progressable progress)
throws IOException {
- super(new PureJavaCrc32(), fs.getBytesPerSum(), 4);
+ super(DataChecksum.newCrc32(), fs.getBytesPerSum(), 4);
int bytesPerSum = fs.getBytesPerSum();
this.datas = fs.getRawFileSystem().create(file, overwrite, bufferSize,
replication, blockSize, progress);
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFs.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFs.java?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFs.java
(original)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFs.java
Wed Jun 25 02:22:15 2014
@@ -18,7 +18,9 @@
package org.apache.hadoop.fs;
-import java.io.*;
+import java.io.EOFException;
+import java.io.FileNotFoundException;
+import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.channels.ClosedChannelException;
import java.util.ArrayList;
@@ -31,8 +33,8 @@ import org.apache.hadoop.classification.
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.Options.ChecksumOpt;
import org.apache.hadoop.fs.permission.FsPermission;
+import org.apache.hadoop.util.DataChecksum;
import org.apache.hadoop.util.Progressable;
-import org.apache.hadoop.util.PureJavaCrc32;
/**
* Abstract Checksumed Fs.
@@ -139,7 +141,7 @@ public abstract class ChecksumFs extends
throw new IOException("Not a checksum file: "+sumFile);
}
this.bytesPerSum = sums.readInt();
- set(fs.verifyChecksum, new PureJavaCrc32(), bytesPerSum, 4);
+ set(fs.verifyChecksum, DataChecksum.newCrc32(), bytesPerSum, 4);
} catch (FileNotFoundException e) { // quietly ignore
set(fs.verifyChecksum, null, 1, 0);
} catch (IOException e) { // loudly ignore
@@ -335,7 +337,7 @@ public abstract class ChecksumFs extends
final short replication, final long blockSize,
final Progressable progress, final ChecksumOpt checksumOpt,
final boolean createParent) throws IOException {
- super(new PureJavaCrc32(), fs.getBytesPerSum(), 4);
+ super(DataChecksum.newCrc32(), fs.getBytesPerSum(), 4);
// checksumOpt is passed down to the raw fs. Unless it implements
// checksum impelemts internally, checksumOpt will be ignored.
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipDecompressor.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipDecompressor.java?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipDecompressor.java
(original)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipDecompressor.java
Wed Jun 25 02:22:15 2014
@@ -19,12 +19,13 @@
package org.apache.hadoop.io.compress.zlib;
import java.io.IOException;
+import java.util.zip.Checksum;
import java.util.zip.DataFormatException;
import java.util.zip.Inflater;
-import org.apache.hadoop.util.PureJavaCrc32;
import org.apache.hadoop.io.compress.Decompressor;
import org.apache.hadoop.io.compress.DoNotPool;
+import org.apache.hadoop.util.DataChecksum;
/**
* A {@link Decompressor} based on the popular gzip compressed file format.
@@ -54,7 +55,7 @@ public class BuiltInGzipDecompressor imp
private int headerBytesRead = 0;
private int trailerBytesRead = 0;
private int numExtraFieldBytesRemaining = -1;
- private PureJavaCrc32 crc = new PureJavaCrc32();
+ private Checksum crc = DataChecksum.newCrc32();
private boolean hasExtraField = false;
private boolean hasFilename = false;
private boolean hasComment = false;
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java
(original)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java
Wed Jun 25 02:22:15 2014
@@ -22,6 +22,7 @@ import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
+import java.util.zip.CRC32;
import java.util.zip.Checksum;
import org.apache.hadoop.classification.InterfaceAudience;
@@ -72,6 +73,13 @@ public class DataChecksum implements Che
}
}
+ /**
+ * Create a Crc32 Checksum object. The implementation of the Crc32 algorithm
+ * is chosen depending on the platform.
+ */
+ public static Checksum newCrc32() {
+ return Shell.isJava7OrAbove()? new CRC32(): new PureJavaCrc32();
+ }
public static DataChecksum newDataChecksum(Type type, int bytesPerChecksum )
{
if ( bytesPerChecksum <= 0 ) {
@@ -82,7 +90,7 @@ public class DataChecksum implements Che
case NULL :
return new DataChecksum(type, new ChecksumNull(), bytesPerChecksum );
case CRC32 :
- return new DataChecksum(type, new PureJavaCrc32(), bytesPerChecksum );
+ return new DataChecksum(type, newCrc32(), bytesPerChecksum );
case CRC32C:
return new DataChecksum(type, new PureJavaCrc32C(), bytesPerChecksum);
default:
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/PureJavaCrc32.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/PureJavaCrc32.java?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/PureJavaCrc32.java
(original)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/PureJavaCrc32.java
Wed Jun 25 02:22:15 2014
@@ -57,38 +57,31 @@ public class PureJavaCrc32 implements Ch
}
@Override
- public void update(byte[] b, int off, int len) {
+ public void update(final byte[] b, final int offset, final int len) {
int localCrc = crc;
- while(len > 7) {
- final int c0 =(b[off+0] ^ localCrc) & 0xff;
- final int c1 =(b[off+1] ^ (localCrc >>>= 8)) & 0xff;
- final int c2 =(b[off+2] ^ (localCrc >>>= 8)) & 0xff;
- final int c3 =(b[off+3] ^ (localCrc >>>= 8)) & 0xff;
- localCrc = (T[T8_7_start + c0] ^ T[T8_6_start + c1])
- ^ (T[T8_5_start + c2] ^ T[T8_4_start + c3]);
+ final int remainder = len & 0x7;
+ int i = offset;
+ for(final int end = offset + len - remainder; i < end; i += 8) {
+ final int x = localCrc
+ ^ ((((b[i ] << 24) >>> 24) + ((b[i+1] << 24) >>> 16))
+ + (((b[i+2] << 24) >>> 8 ) + (b[i+3] << 24)));
- final int c4 = b[off+4] & 0xff;
- final int c5 = b[off+5] & 0xff;
- final int c6 = b[off+6] & 0xff;
- final int c7 = b[off+7] & 0xff;
-
- localCrc ^= (T[T8_3_start + c4] ^ T[T8_2_start + c5])
- ^ (T[T8_1_start + c6] ^ T[T8_0_start + c7]);
-
- off += 8;
- len -= 8;
+ localCrc = ((T[((x << 24) >>> 24) + 0x700] ^ T[((x << 16) >>> 24) +
0x600])
+ ^ (T[((x << 8) >>> 24) + 0x500] ^ T[ (x >>> 24) +
0x400]))
+ ^ ((T[((b[i+4] << 24) >>> 24) + 0x300] ^ T[((b[i+5] << 24) >>>
24) + 0x200])
+ ^ (T[((b[i+6] << 24) >>> 24) + 0x100] ^ T[((b[i+7] << 24) >>>
24)]));
}
/* loop unroll - duff's device style */
- switch(len) {
- case 7: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
- case 6: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
- case 5: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
- case 4: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
- case 3: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
- case 2: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
- case 1: localCrc = (localCrc >>> 8) ^ T[T8_0_start + ((localCrc ^
b[off++]) & 0xff)];
+ switch(remainder) {
+ case 7: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
+ case 6: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
+ case 5: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
+ case 4: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
+ case 3: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
+ case 2: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
+ case 1: localCrc = (localCrc >>> 8) ^ T[((localCrc ^ b[i++]) << 24) >>>
24];
default:
/* nothing */
}
@@ -99,24 +92,15 @@ public class PureJavaCrc32 implements Ch
@Override
final public void update(int b) {
- crc = (crc >>> 8) ^ T[T8_0_start + ((crc ^ b) & 0xff)];
+ crc = (crc >>> 8) ^ T[(((crc ^ b) << 24) >>> 24)];
}
/*
* CRC-32 lookup tables generated by the polynomial 0xEDB88320.
* See also TestPureJavaCrc32.Table.
*/
- private static final int T8_0_start = 0*256;
- private static final int T8_1_start = 1*256;
- private static final int T8_2_start = 2*256;
- private static final int T8_3_start = 3*256;
- private static final int T8_4_start = 4*256;
- private static final int T8_5_start = 5*256;
- private static final int T8_6_start = 6*256;
- private static final int T8_7_start = 7*256;
-
private static final int[] T = new int[] {
- /* T8_0 */
+ /* T8_0 */
0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
Modified:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestPureJavaCrc32.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestPureJavaCrc32.java?rev=1605239&r1=1605238&r2=1605239&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestPureJavaCrc32.java
(original)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestPureJavaCrc32.java
Wed Jun 25 02:22:15 2014
@@ -20,12 +20,14 @@ package org.apache.hadoop.util;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;
+import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.Random;
import java.util.zip.CRC32;
import java.util.zip.Checksum;
+
import org.junit.Assert;
import org.junit.Test;
@@ -187,12 +189,18 @@ public class TestPureJavaCrc32 {
long polynomial = Long.parseLong(args[0], 16);
int i = 8;
- final PrintStream out = new PrintStream(
- new FileOutputStream("table" + i + ".txt"), true);
final Table t = new Table(i, 16, polynomial);
final String s = t.toString();
System.out.println(s);
- out.println(s);
+
+ //print to a file
+ final PrintStream out = new PrintStream(
+ new FileOutputStream("table" + i + ".txt"), true);
+ try {
+ out.println(s);
+ } finally {
+ out.close();
+ }
}
}
@@ -210,10 +218,15 @@ public class TestPureJavaCrc32 {
public static final int MAX_LEN = 32*1024*1024; // up to 32MB chunks
public static final int BYTES_PER_SIZE = MAX_LEN * 4;
- static final Checksum zip = new CRC32();
- static final Checksum[] CRCS = {new PureJavaCrc32()};
+ static final Class<? extends Checksum> zip = CRC32.class;
+ static final List<Class<? extends Checksum>> CRCS = new ArrayList<Class<?
extends Checksum>>();
+ static {
+ CRCS.add(zip);
+ CRCS.add(PureJavaCrc32.class);
+ }
+
- public static void main(String args[]) {
+ public static void main(String args[]) throws Exception {
printSystemProperties(System.out);
doBench(CRCS, System.out);
}
@@ -223,76 +236,140 @@ public class TestPureJavaCrc32 {
out.printf(" %" + w + "s |", s);
}
- private static void doBench(final Checksum[] crcs, final PrintStream out) {
- final ArrayList<Checksum> a = new ArrayList<Checksum>();
- a.add(zip);
- for (Checksum c : crcs)
- if(c.getClass() != zip.getClass())
- a.add(c);
- doBench(a, out);
- }
-
- private static void doBench(final List<Checksum> crcs, final PrintStream
out
- ) {
+ private static void doBench(final List<Class<? extends Checksum>> crcs,
+ final PrintStream out) throws Exception {
final byte[] bytes = new byte[MAX_LEN];
new Random().nextBytes(bytes);
// Print header
- out.printf("\nPerformance Table (The unit is MB/sec)\n||");
- final String title = "Num Bytes";
- printCell("Num Bytes", 0, out);
- for (Checksum c : crcs) {
- out.printf("|");
- printCell(c.getClass().getSimpleName(), 8, out);
- }
- out.printf("|\n");
+ out.printf("\nPerformance Table (The unit is MB/sec; #T = #Theads)\n");
// Warm up implementations to get jit going.
- for (Checksum c : crcs) {
- doBench(c, bytes, 2, null);
- doBench(c, bytes, 2101, null);
+ for (Class<? extends Checksum> c : crcs) {
+ doBench(c, 1, bytes, 2);
+ doBench(c, 1, bytes, 2101);
+ }
+
+ // Test on a variety of sizes with different number of threads
+ for (int size = 32; size <= MAX_LEN; size <<= 1) {
+ doBench(crcs, bytes, size, out);
+ }
+ }
+
+ private static void doBench(final List<Class<? extends Checksum>> crcs,
+ final byte[] bytes, final int size, final PrintStream out) throws
Exception {
+ final String numBytesStr = " #Bytes ";
+ final String numThreadsStr = "#T";
+ final String diffStr = "% diff";
+
+ out.print('|');
+ printCell(numBytesStr, 0, out);
+ printCell(numThreadsStr, 0, out);
+ for (int i = 0; i < crcs.size(); i++) {
+ final Class<? extends Checksum> c = crcs.get(i);
+ out.print('|');
+ printCell(c.getSimpleName(), 8, out);
+ for(int j = 0; j < i; j++) {
+ printCell(diffStr, diffStr.length(), out);
+ }
}
+ out.printf("\n");
- // Test on a variety of sizes
- for (int size = 1; size < MAX_LEN; size *= 2) {
+ for(int numThreads = 1; numThreads <= 16; numThreads <<= 1) {
out.printf("|");
- printCell(String.valueOf(size), title.length()+1, out);
+ printCell(String.valueOf(size), numBytesStr.length(), out);
+ printCell(String.valueOf(numThreads), numThreadsStr.length(), out);
- Long expected = null;
- for(Checksum c : crcs) {
+ BenchResult expected = null;
+ final List<BenchResult> previous = new ArrayList<BenchResult>();
+ for(Class<? extends Checksum> c : crcs) {
System.gc();
- final long result = doBench(c, bytes, size, out);
- if(c.getClass() == zip.getClass()) {
+
+ final BenchResult result = doBench(c, numThreads, bytes, size);
+ printCell(String.format("%9.1f", result.mbps),
+ c.getSimpleName().length()+1, out);
+
+ //check result
+ if(c == zip) {
expected = result;
- } else if (result != expected) {
- throw new RuntimeException(c.getClass() + " has bugs!");
+ } else if (expected == null) {
+ throw new RuntimeException("The first class is "
+ + c.getName() + " but not " + zip.getName());
+ } else if (result.value != expected.value) {
+ throw new RuntimeException(c + " has bugs!");
+ }
+
+ //compare result with previous
+ for(BenchResult p : previous) {
+ final double diff = (result.mbps - p.mbps) / p.mbps * 100;
+ printCell(String.format("%5.1f%%", diff), diffStr.length(), out);
}
-
+ previous.add(result);
}
out.printf("\n");
}
}
- private static long doBench(Checksum crc, byte[] bytes, int size,
- PrintStream out) {
- final String name = crc.getClass().getSimpleName();
- final int trials = BYTES_PER_SIZE / size;
-
- final long st = System.nanoTime();
- crc.reset();
- for (int i = 0; i < trials; i++) {
- crc.update(bytes, 0, size);
- }
- final long result = crc.getValue();
- final long et = System.nanoTime();
-
- double mbProcessed = trials * size / 1024.0 / 1024.0;
- double secsElapsed = (et - st) / 1000000000.0d;
- if (out != null) {
- final String s = String.format("%9.3f", mbProcessed/secsElapsed);
- printCell(s, name.length()+1, out);
+ private static BenchResult doBench(Class<? extends Checksum> clazz,
+ final int numThreads, final byte[] bytes, final int size)
+ throws Exception {
+
+ final Thread[] threads = new Thread[numThreads];
+ final BenchResult[] results = new BenchResult[threads.length];
+
+ {
+ final int trials = BYTES_PER_SIZE / size;
+ final double mbProcessed = trials * size / 1024.0 / 1024.0;
+ final Constructor<? extends Checksum> ctor = clazz.getConstructor();
+
+ for(int i = 0; i < threads.length; i++) {
+ final int index = i;
+ threads[i] = new Thread() {
+ final Checksum crc = ctor.newInstance();
+
+ @Override
+ public void run() {
+ final long st = System.nanoTime();
+ crc.reset();
+ for (int i = 0; i < trials; i++) {
+ crc.update(bytes, 0, size);
+ }
+ final long et = System.nanoTime();
+ double secsElapsed = (et - st) / 1000000000.0d;
+ results[index] = new BenchResult(crc.getValue(),
mbProcessed/secsElapsed);
+ }
+ };
+ }
+ }
+
+ for(int i = 0; i < threads.length; i++) {
+ threads[i].start();
+ }
+ for(int i = 0; i < threads.length; i++) {
+ threads[i].join();
+ }
+
+ final long expected = results[0].value;
+ double sum = results[0].mbps;
+ for(int i = 1; i < results.length; i++) {
+ if (results[i].value != expected) {
+ throw new AssertionError(clazz.getSimpleName() + " results not
matched.");
+ }
+ sum += results[i].mbps;
+ }
+ return new BenchResult(expected, sum/results.length);
+ }
+
+ private static class BenchResult {
+ /** CRC value */
+ final long value;
+ /** Speed (MB per second) */
+ final double mbps;
+
+ BenchResult(long value, double mbps) {
+ this.value = value;
+ this.mbps = mbps;
}
- return result;
}
private static void printSystemProperties(PrintStream out) {
