Adding more speed improvements, going for first again.
Updating script
This commit is contained in:
Roy van Rijn
Gunnar Morling
parent
631722158c
commit
3a2e0ed267
@ -15,7 +15,8 @@
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# limitations under the License.
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#
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sdk use java 21.0.1-graal
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source "$HOME/.sdkman/bin/sdkman-init.sh"
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sdk use java 21.0.1-graal 1>&2
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# Added for fun, doesn't seem to be making a difference...
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if [ -f "target/calculate_average_royvanrijn.jsa" ]; then
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JAVA_OPTS="-XX:SharedArchiveFile=target/calculate_average_royvanrijn.jsa -Xshare:on"
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@ -28,8 +28,10 @@ import java.nio.file.StandardOpenOption;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Objects;
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import java.util.TreeMap;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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/**
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* Changelog:
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@ -47,6 +49,7 @@ import java.util.stream.Collectors;
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* Segmenting files: 3150 ms (based on spullara's code)
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* Not using SWAR for EOL: 2850 ms
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* Inlining hash calculation: 2450 ms
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* Replacing branchless code: 2200 ms (sometimes we need to kill the things we love)
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*
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* Best performing JVM on MacBook M2 Pro: 21.0.1-graal
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* `sdk use java 21.0.1-graal`
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@ -55,8 +58,8 @@ import java.util.stream.Collectors;
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public class CalculateAverage_royvanrijn {
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private static final String FILE = "./measurements.txt";
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// private static final String FILE = "./src/test/resources/samples/measurements-10000-unique-keys.txt";
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// mutable state now instead of records, ugh, less instantiation.
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static final class Measurement {
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int min, max, count;
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long sum;
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@ -96,29 +99,6 @@ public class CalculateAverage_royvanrijn {
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// new CalculateAverage_royvanrijn().runTests();
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}
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private void testInput(final String inputString, final int start, final boolean bigEndian, final int[] expectedDelimiterAndHash, final long[] expectedCityNameLong) {
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byte[] input = inputString.getBytes(StandardCharsets.UTF_8);
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ByteBuffer buffer = ByteBuffer.wrap(input).order(bigEndian ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN);
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int[] output = new int[2];
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long[] cityName = new long[128];
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findNextDelimiterAndCalculateHash(buffer, SEPARATOR_PATTERN, start, buffer.limit(), output, cityName, bigEndian);
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if (!Arrays.equals(output, expectedDelimiterAndHash)) {
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System.out.println("Error in delimiter or hash");
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System.out.println("Expected: " + Arrays.toString(expectedDelimiterAndHash));
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System.out.println("Received: " + Arrays.toString(output));
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}
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int amountLong = 1 + ((output[0] - start) >>> 3);
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if (!Arrays.equals(cityName, 0, amountLong, expectedCityNameLong, 0, amountLong)) {
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System.out.println("Error in long array");
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System.out.println("Expected: " + Arrays.toString(expectedCityNameLong));
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System.out.println("Received: " + Arrays.toString(cityName));
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}
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}
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private void run() throws Exception {
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var results = getFileSegments(new File(FILE)).stream().map(segment -> {
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@ -128,8 +108,7 @@ public class CalculateAverage_royvanrijn {
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var bb = fileChannel.map(FileChannel.MapMode.READ_ONLY, segment.start(), segmentEnd - segment.start());
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// Work with any UTF-8 city name, up to 100 in length:
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var buffer = new byte[106]; // 100 + ; + -XX.X + \n
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var cityNameAsLongArray = new long[13]; // 13*8=104=kenough.
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var cityNameAsLongArray = new long[16];
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var delimiterPointerAndHash = new int[2];
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// Calculate using native ordering (fastest?):
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@ -143,39 +122,39 @@ public class CalculateAverage_royvanrijn {
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int limit = bb.limit();
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while ((startPointer = bb.position()) < limit) {
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int delimiterPointer, endPointer;
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// SWAR method to find delimiter *and* record the cityname as long[] *and* calculate a hash:
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findNextDelimiterAndCalculateHash(bb, SEPARATOR_PATTERN, startPointer, limit, delimiterPointerAndHash, cityNameAsLongArray, bufferIsBigEndian);
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int delimiterPointer = delimiterPointerAndHash[0];
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delimiterPointer = delimiterPointerAndHash[0];
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// Simple lookup is faster for '\n' (just three options)
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int endPointer;
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if (delimiterPointer >= limit) {
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bb.position(limit); // skip to next line.
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return measurements;
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}
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if (bb.get(delimiterPointer + 4) == '\n') {
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endPointer = delimiterPointer + 4;
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}
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else if (bb.get(delimiterPointer + 5) == '\n') {
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endPointer = delimiterPointer + 5;
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}
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else {
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endPointer = delimiterPointer + 6;
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}
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// Read the entry in a single get():
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bb.get(buffer, 0, endPointer - startPointer);
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bb.position(endPointer + 1); // skip to next line.
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// Extract the measurement value (10x):
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final int cityNameLength = delimiterPointer - startPointer;
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final int measuredValueLength = endPointer - delimiterPointer - 1;
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final int measuredValue = branchlessParseInt(buffer, cityNameLength + 1, measuredValueLength);
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int measuredValue;
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int neg = 1;
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if (bb.get(++delimiterPointer) == '-') {
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neg = -1;
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delimiterPointer++;
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}
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byte dot;
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if ((dot = (bb.get(delimiterPointer + 1))) == '.') {
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measuredValue = neg * ((bb.get(delimiterPointer)) * 10 + (bb.get(delimiterPointer + 2)) - 528);
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endPointer = delimiterPointer + 3;
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}
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else {
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measuredValue = neg * (bb.get(delimiterPointer) * 100 + dot * 10 + bb.get(delimiterPointer + 3) - 5328);
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endPointer = delimiterPointer + 4;
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}
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// Store everything in a custom hashtable:
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measurements.update(buffer, cityNameLength, delimiterPointerAndHash[1], cityNameAsLongArray).updateWith(measuredValue);
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measurements.update(cityNameAsLongArray, bb, cityNameLength, delimiterPointerAndHash[1]).updateWith(measuredValue);
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bb.position(endPointer + 1); // skip to next line.
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}
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return measurements;
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}
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@ -183,61 +162,18 @@ public class CalculateAverage_royvanrijn {
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throw new RuntimeException(e);
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}
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}).parallel()
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.flatMap(v -> v.values.stream())
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.flatMap(v -> v.get())
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.collect(Collectors.toMap(e -> e.cityName, MeasurementRepository.Entry::measurement, Measurement::updateWith, TreeMap::new));
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System.out.println(results);
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// System.out.println("Processed: " + results.entrySet().stream().mapToLong(e -> e.getValue().count).sum());
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}
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/**
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* -------- This section contains SWAR code (SIMD Within A Register) which processes a bytebuffer as longs to find values:
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*/
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private static final long SEPARATOR_PATTERN = compilePattern((byte) ';');
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private static final long[] PARTIAL_INDEX_MASKS = new long[]{ 0L, 255L, 65535L, 16777215L, 4294967295L, 1099511627775L, 281474976710655L, 72057594037927935L };
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public void runTests() {
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// Method used for debugging purposes, easy to make mistakes with all the bit hacking.
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// These all have the same hashes:
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testInput("Delft;-12.4", 0, true, new int[]{ 5, 1718384401 }, new long[]{ 499934586180L });
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testInput("aDelft;-12.4", 1, true, new int[]{ 6, 1718384401 }, new long[]{ 499934586180L });
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testInput("Delft;-12.4", 0, false, new int[]{ 5, 1718384401 }, new long[]{ 499934586180L });
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testInput("aDelft;-12.4", 1, false, new int[]{ 6, 1718384401 }, new long[]{ 499934586180L });
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testInput("Rotterdam;-12.4", 0, true, new int[]{ 9, -784321989 }, new long[]{ 7017859899421126482L, 109L });
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testInput("abcdefghijklmnpoqrstuvwxyzRotterdam;-12.4", 26, true, new int[]{ 35, -784321989 }, new long[]{ 7017859899421126482L, 109L });
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testInput("abcdefghijklmnpoqrstuvwxyzARotterdam;-12.4", 27, true, new int[]{ 36, -784321989 }, new long[]{ 7017859899421126482L, 109L });
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testInput("Rotterdam;-12.4", 0, false, new int[]{ 9, -784321989 }, new long[]{ 7017859899421126482L, 109L });
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testInput("abcdefghijklmnpoqrstuvwxyzRotterdam;-12.4", 26, false, new int[]{ 35, -784321989 }, new long[]{ 7017859899421126482L, 109L });
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testInput("abcdefghijklmnpoqrstuvwxyzARotterdam;-12.4", 27, false, new int[]{ 36, -784321989 }, new long[]{ 7017859899421126482L, 109L });
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// These have different hashes from the strings above:
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testInput("abcdefghijklmnpoqrstuvwxyzAROtterdam;-12.4", 27, true, new int[]{ 36, -792194501 }, new long[]{ 7017859899421118290L, 109L });
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testInput("abcdefghijklmnpoqrstuvwxyzAROtterdam;-12.4", 27, false, new int[]{ 36, -792194501 }, new long[]{ 7017859899421118290L, 109L });
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MeasurementRepository repository = new MeasurementRepository();
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// Simulate adding two entries with the same hash:
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byte[] b1 = "City1;10.0".getBytes();
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byte[] b2 = "City2;41.1".getBytes();
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repository.update(b1, 5, 1234, new long[]{ 1234L });
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repository.update(b2, 5, 1234, new long[]{ 4321L });
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// And update the same record shouldn't add a third (this happened):
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repository.update(b1, 5, 1234, new long[]{ 1234L });
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if (repository.values.size() != 2) {
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System.out.println("Error, should have two entries:");
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System.out.println(repository.values);
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}
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MeasurementRepository.Entry firstInserted = repository.values.getFirst();
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if (!firstInserted.cityName.equals("City1")) {
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System.out.println("Error, should have correct name: " + firstInserted.cityName);
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}
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}
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/**
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* Already looping the longs here, lets shoehorn in making a hash
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@ -249,35 +185,43 @@ public class CalculateAverage_royvanrijn {
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int lCnt = 0;
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for (i = start; i <= limit - 8; i += 8) {
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long word = bb.getLong(i);
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if (bufferBigEndian)
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if (bufferBigEndian) {
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word = Long.reverseBytes(word); // Reversing the bytes is the cheapest way to do this
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int index = firstAnyPattern(word, pattern);
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if (index < Long.BYTES) {
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final long partialHash = word & PARTIAL_INDEX_MASKS[index];
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asLong[lCnt] = partialHash;
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hash = 961 * hash + 31 * (int) (partialHash >>> 32) + (int) partialHash;
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}
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final long match = word ^ pattern;
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long mask = ((match - 0x0101010101010101L) & ~match) & 0x8080808080808080L;
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if (mask != 0) {
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final int index = Long.numberOfTrailingZeros(mask) >> 3;
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output[0] = (i + index);
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output[1] = hash;
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final long partialHash = word & ((mask >> 7) - 1);
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asLong[lCnt] = partialHash;
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output[1] = longHashStep(hash, partialHash);
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return;
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}
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asLong[lCnt++] = word;
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hash = 961 * hash + 31 * (int) (word >>> 32) + (int) word;
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hash = longHashStep(hash, word);
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}
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// Handle remaining bytes
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// Handle remaining bytes near the limit of the buffer:
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long partialHash = 0;
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int len = 0;
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for (; i < limit; i++) {
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byte read;
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if ((read = bb.get(i)) == (byte) pattern) {
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asLong[lCnt] = partialHash;
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hash = 961 * hash + 31 * (int) (partialHash >>> 32) + (int) partialHash;
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output[0] = i;
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output[1] = hash;
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output[1] = longHashStep(hash, partialHash);
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return;
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}
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partialHash = partialHash << 8 | read;
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partialHash = partialHash | ((long) read << (len << 3));
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len++;
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}
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output[0] = limit; // delimiter not found
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output[1] = hash;
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}
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private static int longHashStep(final int hash, final long word) {
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return 31 * hash + (int) (word ^ (word >>> 32));
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}
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private static long compilePattern(final byte value) {
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@ -285,18 +229,9 @@ public class CalculateAverage_royvanrijn {
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((long) value << 24) | ((long) value << 16) | ((long) value << 8) | (long) value;
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}
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private static int firstAnyPattern(final long word, final long pattern) {
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final long match = word ^ pattern;
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long mask = match - 0x0101010101010101L;
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mask &= ~match;
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mask &= 0x8080808080808080L;
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return Long.numberOfTrailingZeros(mask) >> 3;
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}
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record FileSegment(long start, long end) {
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}
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/** Using this way to segment the file is much prettier, from spullara */
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private static List<FileSegment> getFileSegments(final File file) throws IOException {
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final int numberOfSegments = Runtime.getRuntime().availableProcessors();
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final long fileSize = file.length();
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@ -307,52 +242,28 @@ public class CalculateAverage_royvanrijn {
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return segments;
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}
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try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r")) {
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for (int i = 0; i < numberOfSegments; i++) {
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long segStart = i * segmentSize;
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long segEnd = (i == numberOfSegments - 1) ? fileSize : segStart + segmentSize;
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segStart = findSegment(i, 0, randomAccessFile, segStart, segEnd);
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segEnd = findSegment(i, numberOfSegments - 1, randomAccessFile, segEnd, fileSize);
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long segStart = 0;
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long segEnd = segmentSize;
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while (segStart < fileSize) {
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segEnd = findSegment(randomAccessFile, segEnd, fileSize);
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segments.add(new FileSegment(segStart, segEnd));
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segStart = segEnd; // Just re-use the end and go from there.
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segEnd = Math.min(fileSize, segEnd + segmentSize);
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}
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}
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return segments;
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}
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private static long findSegment(final int i, final int skipSegment, RandomAccessFile raf, long location, final long fileSize) throws IOException {
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if (i != skipSegment) {
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raf.seek(location);
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while (location < fileSize) {
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location++;
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if (raf.read() == '\n')
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return location;
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}
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private static long findSegment(RandomAccessFile raf, long location, final long fileSize) throws IOException {
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raf.seek(location);
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while (location < fileSize) {
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location++;
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if (raf.read() == '\n')
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return location;
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}
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return location;
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}
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/**
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* Branchless parser, goes from String to int (10x):
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* "-1.2" to -12
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* "40.1" to 401
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* etc.
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*
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* @param input
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* @return int value x10
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*/
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private static int branchlessParseInt(final byte[] input, final int start, final int length) {
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// 0 if positive, 1 if negative
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final int negative = ~(input[start] >> 4) & 1;
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// 0 if nr length is 3, 1 if length is 4
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final int has4 = ((length - negative) >> 2) & 1;
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final int digit1 = input[start + negative] - '0';
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final int digit2 = input[start + negative + has4];
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final int digit3 = input[start + negative + has4 + 2];
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return (-negative ^ (has4 * (digit1 * 100) + digit2 * 10 + digit3 - 528) - negative); // 528 == ('0' * 10 + '0')
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}
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// branchless max (unprecise for large numbers, but good enough)
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static int max(final int a, final int b) {
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final int diff = a - b;
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@ -373,88 +284,81 @@ public class CalculateAverage_royvanrijn {
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* So I've written an extremely simple linear probing hashmap that should work well enough.
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*/
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class MeasurementRepository {
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private int size = 16384;// 16384; // Much larger than the number of cities, needs power of two
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private int[] indices = new int[size]; // Hashtable is just an int[]
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private int tableSize = 1 << 20; // can grow in theory, made large enough not to (this is faster)
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private int tableMask = (tableSize - 1);
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private int tableLimit = (int) (tableSize * LOAD_FACTOR);
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private int tableFilled = 0;
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private static final float LOAD_FACTOR = 0.8f;
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MeasurementRepository() {
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populateEmptyIndices(indices);
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}
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private Entry[] table = new Entry[tableSize];
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private void populateEmptyIndices(int[] array) {
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// Optimized fill with -1, fastest method:
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int len = array.length;
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array[0] = -1;
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// Value of i will be [1, 2, 4, 8, 16, 32, ..., len]
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for (int i = 1; i < len; i += i) {
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System.arraycopy(array, 0, array, i, i);
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}
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}
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private final List<Entry> values = new ArrayList<>(512);
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record Entry(int hash, long[] cityNameAsLong, String cityName, Measurement measurement) {
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record Entry(int hash, long[] nameBytesInLong, String cityName, Measurement measurement) {
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@Override
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public String toString() {
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return cityName + "=" + measurement;
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}
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}
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public Measurement update(byte[] buffer, int length, int calculatedHash, long[] cityNameAsLongArray) {
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public Measurement update(long[] nameBytesInLong, ByteBuffer bb, int length, int calculatedHash) {
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final int cityNameAsLongLength = 1 + (length >>> 3); // amount of longs that captures this cityname
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final int nameBytesInLongLength = 1 + (length >>> 3);
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int hashtableIndex = (size - 1) & calculatedHash;
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int valueIndex;
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Entry retrievedEntry = null;
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while (true) { // search for the right spot
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if ((valueIndex = indices[hashtableIndex]) == -1) {
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break; // Empty slot found, stop the loop
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}
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else {
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// Non-empty slot, retrieve entry
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if ((retrievedEntry = values.get(valueIndex)).hash == calculatedHash &&
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arrayEquals(retrievedEntry.cityNameAsLong, cityNameAsLongArray, cityNameAsLongLength)) {
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break; // Both hash and cityname match, stop the loop
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}
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}
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// Move to the next index
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hashtableIndex = (hashtableIndex + 1) % size;
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int index = calculatedHash & tableMask;
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||||
Entry tableEntry;
|
||||
while ((tableEntry = table[index]) != null
|
||||
&& (tableEntry.hash != calculatedHash || !arrayEquals(tableEntry.nameBytesInLong, nameBytesInLong, nameBytesInLongLength))) { // search for the right spot
|
||||
index = (index + 1) & tableMask;
|
||||
}
|
||||
|
||||
if (valueIndex >= 0) {
|
||||
return retrievedEntry.measurement;
|
||||
if (tableEntry != null) {
|
||||
return tableEntry.measurement;
|
||||
}
|
||||
|
||||
// --- This is a brand new entry, insert into the hashtable and do the extra calculations (once!)
|
||||
// --- This is a brand new entry, insert into the hashtable and do the extra calculations (once!) do slower calculations here.
|
||||
Measurement measurement = new Measurement();
|
||||
|
||||
// Keep the already processed longs for fast equals:
|
||||
long[] cityNameAsLongArrayCopy = new long[cityNameAsLongLength];
|
||||
System.arraycopy(cityNameAsLongArray, 0, cityNameAsLongArrayCopy, 0, cityNameAsLongLength);
|
||||
// Now create a string:
|
||||
byte[] buffer = new byte[length];
|
||||
bb.get(buffer, 0, length);
|
||||
String cityName = new String(buffer, 0, length);
|
||||
|
||||
Entry toAdd = new Entry(calculatedHash, cityNameAsLongArrayCopy, new String(buffer, 0, length), new Measurement());
|
||||
// Store the long[] for faster equals:
|
||||
long[] nameBytesInLongCopy = new long[nameBytesInLongLength];
|
||||
System.arraycopy(nameBytesInLong, 0, nameBytesInLongCopy, 0, nameBytesInLongLength);
|
||||
|
||||
// Code to regrow (if we get more unique entries): (not needed/not optimized yet)
|
||||
// if (values.size() > size / 2) {
|
||||
// // We probably don't want this...
|
||||
//
|
||||
// int newSize = size << 1;
|
||||
// int[] newIndices = new int[newSize];
|
||||
// populateEmptyIndices(newIndices);
|
||||
// for (int i = 0; i < values.size(); i++) {
|
||||
// Entry e = values.get(i);
|
||||
// int updatedIndex = (newSize - 1) & e.hash;
|
||||
// newIndices[updatedIndex] = i;
|
||||
// }
|
||||
// indices = newIndices;
|
||||
// size = newSize;
|
||||
// }
|
||||
indices[hashtableIndex] = values.size();
|
||||
// And add entry:
|
||||
Entry toAdd = new Entry(calculatedHash, nameBytesInLongCopy, cityName, measurement);
|
||||
table[index] = toAdd;
|
||||
|
||||
// Resize the table if filled too much:
|
||||
if (++tableFilled > tableLimit) {
|
||||
resizeTable();
|
||||
}
|
||||
|
||||
values.add(toAdd);
|
||||
return toAdd.measurement;
|
||||
}
|
||||
|
||||
private void resizeTable() {
|
||||
// Resize the table:
|
||||
Entry[] oldEntries = table;
|
||||
table = new Entry[tableSize <<= 2]; // x2
|
||||
tableMask = (tableSize - 1);
|
||||
tableLimit = (int) (tableSize * LOAD_FACTOR);
|
||||
|
||||
for (Entry entry : oldEntries) {
|
||||
if (entry != null) {
|
||||
int updatedTableIndex = entry.hash & tableMask;
|
||||
while (table[updatedTableIndex] != null) {
|
||||
updatedTableIndex = (updatedTableIndex + 1) & tableMask;
|
||||
}
|
||||
table[updatedTableIndex] = entry;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
public Stream<Entry> get() {
|
||||
return Arrays.stream(table).filter(Objects::nonNull);
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
@ -467,4 +371,50 @@ public class CalculateAverage_royvanrijn {
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
public void runTests() {
|
||||
// Method used for debugging purposes, easy to make mistakes with all the bit hacking.
|
||||
|
||||
// These all have the same hashes:
|
||||
testInput("Delft;-12.4", 0, true, new int[]{ 5, 1718384401 }, new long[]{ 499934586180L });
|
||||
testInput("aDelft;-12.4", 1, true, new int[]{ 6, 1718384401 }, new long[]{ 499934586180L });
|
||||
|
||||
testInput("Delft;-12.4", 0, false, new int[]{ 5, 1718384401 }, new long[]{ 499934586180L });
|
||||
testInput("aDelft;-12.4", 1, false, new int[]{ 6, 1718384401 }, new long[]{ 499934586180L });
|
||||
|
||||
testInput("Rotterdam;-12.4", 0, true, new int[]{ 9, -784321989 }, new long[]{ 7017859899421126482L, 109L });
|
||||
testInput("abcdefghijklmnpoqrstuvwxyzRotterdam;-12.4", 26, true, new int[]{ 35, -784321989 }, new long[]{ 7017859899421126482L, 109L });
|
||||
testInput("abcdefghijklmnpoqrstuvwxyzARotterdam;-12.4", 27, true, new int[]{ 36, -784321989 }, new long[]{ 7017859899421126482L, 109L });
|
||||
|
||||
testInput("Rotterdam;-12.4", 0, false, new int[]{ 9, -784321989 }, new long[]{ 7017859899421126482L, 109L });
|
||||
testInput("abcdefghijklmnpoqrstuvwxyzRotterdam;-12.4", 26, false, new int[]{ 35, -784321989 }, new long[]{ 7017859899421126482L, 109L });
|
||||
testInput("abcdefghijklmnpoqrstuvwxyzARotterdam;-12.4", 27, false, new int[]{ 36, -784321989 }, new long[]{ 7017859899421126482L, 109L });
|
||||
|
||||
// These have different hashes from the strings above:
|
||||
testInput("abcdefghijklmnpoqrstuvwxyzAROtterdam;-12.4", 27, true, new int[]{ 36, -792194501 }, new long[]{ 7017859899421118290L, 109L });
|
||||
testInput("abcdefghijklmnpoqrstuvwxyzAROtterdam;-12.4", 27, false, new int[]{ 36, -792194501 }, new long[]{ 7017859899421118290L, 109L });
|
||||
}
|
||||
|
||||
private void testInput(final String inputString, final int start, final boolean bigEndian, final int[] expectedDelimiterAndHash, final long[] expectedCityNameLong) {
|
||||
|
||||
byte[] input = inputString.getBytes(StandardCharsets.UTF_8);
|
||||
|
||||
ByteBuffer buffer = ByteBuffer.wrap(input).order(bigEndian ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN);
|
||||
|
||||
int[] output = new int[2];
|
||||
long[] cityName = new long[128];
|
||||
findNextDelimiterAndCalculateHash(buffer, SEPARATOR_PATTERN, start, buffer.limit(), output, cityName, bigEndian);
|
||||
|
||||
if (!Arrays.equals(output, expectedDelimiterAndHash)) {
|
||||
System.out.println("Error in delimiter or hash");
|
||||
System.out.println("Expected: " + Arrays.toString(expectedDelimiterAndHash));
|
||||
System.out.println("Received: " + Arrays.toString(output));
|
||||
}
|
||||
int amountLong = 1 + ((output[0] - start) >>> 3);
|
||||
if (!Arrays.equals(cityName, 0, amountLong, expectedCityNameLong, 0, amountLong)) {
|
||||
System.out.println("Error in long array");
|
||||
System.out.println("Expected: " + Arrays.toString(expectedCityNameLong));
|
||||
System.out.println("Received: " + Arrays.toString(cityName));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user