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merykitty's attempt

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* first commit

* fix test

* concurrency

* format for easier to follow explanation

* fix large keys

* fix overlapping ranges

* prefetch file

* add comments, remove prefetching

* typo
This commit is contained in:
Quan Anh Mai
2024-01-06 23:01:12 +07:00
committed by GitHub
parent 241d32817e
commit 4fc6034812
2 changed files with 411 additions and 0 deletions
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calculate_average_merykitty.sh Executable file
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#!/bin/sh
#
# Copyright 2023 The original authors
#
# Licensed 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.
#
JAVA_OPTS="--enable-preview --add-modules=jdk.incubator.vector" # -XX:+UnlockDiagnosticVMOptions -XX:PrintAssemblyOptions=intel -XX:CompileCommand=print,*.CalculateAverage_merykitty::iterate"
time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_merykitty

391
src/main/java/dev/morling/onebrc/CalculateAverage_merykitty.java Normal file
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/*
* Copyright 2023 The original authors
*
* Licensed 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 dev.morling.onebrc;
import java.io.IOException;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.ValueLayout;
import java.nio.ByteOrder;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import jdk.incubator.vector.ByteVector;
import jdk.incubator.vector.VectorOperators;
import jdk.incubator.vector.VectorSpecies;
public class CalculateAverage_merykitty {
private static final String FILE = "./measurements.txt";
private static final VectorSpecies<Byte> BYTE_SPECIES = ByteVector.SPECIES_PREFERRED;
private static final ValueLayout.OfLong JAVA_LONG_LT = ValueLayout.JAVA_LONG_UNALIGNED.withOrder(ByteOrder.LITTLE_ENDIAN);
private static final long KEY_MAX_SIZE = 100;
private record ResultRow(double min, double mean, double max) {
public String toString() {
return round(min) + "/" + round(mean) + "/" + round(max);
}
private double round(double value) {
return Math.round(value * 10.0) / 10.0;
}
}
private static class Aggregator {
private long min = Integer.MAX_VALUE;
private long max = Integer.MIN_VALUE;
private long sum;
private long count;
}
// An open-address map that is specialized for this task
private static class PoorManMap {
static final int R_LOAD_FACTOR = 2;
private static class PoorManMapNode {
byte[] data;
long size;
int hash;
Aggregator aggr;
PoorManMapNode(MemorySegment data, long offset, long size, int hash) {
this.hash = hash;
this.size = size;
this.data = new byte[BYTE_SPECIES.vectorByteSize() + (int) KEY_MAX_SIZE];
this.aggr = new Aggregator();
MemorySegment.copy(data, offset, MemorySegment.ofArray(this.data), BYTE_SPECIES.vectorByteSize(), size);
}
}
MemorySegment data;
PoorManMapNode[] nodes;
int size;
PoorManMap(MemorySegment data) {
this.data = data;
this.nodes = new PoorManMapNode[1 << 10];
}
Aggregator indexSimple(long offset, long size, int hash) {
hash = rehash(hash);
int bucketMask = nodes.length - 1;
int bucket = hash & bucketMask;
for (;; bucket = (bucket + 1) & bucketMask) {
PoorManMapNode node = nodes[bucket];
if (node == null) {
this.size++;
if (this.size * R_LOAD_FACTOR > nodes.length) {
grow();
bucketMask = nodes.length - 1;
for (bucket = hash & bucketMask; nodes[bucket] != null; bucket = (bucket + 1) & bucketMask) {
}
}
node = new PoorManMapNode(this.data, offset, size, hash);
nodes[bucket] = node;
return node.aggr;
}
else if (keyEqualScalar(node, offset, size, hash)) {
return node.aggr;
}
}
}
void grow() {
var oldNodes = this.nodes;
var newNodes = new PoorManMapNode[oldNodes.length * 2];
int bucketMask = newNodes.length - 1;
for (var node : oldNodes) {
if (node == null) {
continue;
}
int bucket = node.hash & bucketMask;
for (; newNodes[bucket] != null; bucket = (bucket + 1) & bucketMask) {
}
newNodes[bucket] = node;
}
this.nodes = newNodes;
}
static int rehash(int x) {
x = ((x >>> 16) ^ x) * 0x45d9f3b;
x = ((x >>> 16) ^ x) * 0x45d9f3b;
x = (x >>> 16) ^ x;
return x;
}
private boolean keyEqualScalar(PoorManMapNode node, long offset, long size, int hash) {
if (node.hash != hash || node.size != size) {
return false;
}
// Be simple
for (int i = 0; i < size; i++) {
int c1 = node.data[BYTE_SPECIES.vectorByteSize() + i];
int c2 = data.get(ValueLayout.JAVA_BYTE, offset + i);
if (c1 != c2) {
return false;
}
}
return true;
}
}
// Parse a number that may/may not contain a minus sign followed by a decimal with
// 1 - 2 digits to the left and 1 digits to the right of the separator to a
// fix-precision format. It returns the offset of the next line (presumably followed
// the final digit and a '\n')
private static long parseDataPoint(Aggregator aggr, MemorySegment data, long offset) {
long word = data.get(JAVA_LONG_LT, offset);
// The 4th binary digit of the ascii of a digit is 1 while
// that of the '.' is 0. This finds the decimal separator
// The value can be 12, 20, 28
int decimalSepPos = Long.numberOfTrailingZeros(~word & 0x10101000);
int shift = 28 - decimalSepPos;
// signed is -1 if negative, 0 otherwise
long signed = (~word << 59) >> 63;
long designMask = ~(signed & 0xFF);
// Align the number to a specific position and transform the ascii code
// to actual digit value in each byte
long digits = ((word & designMask) << shift) & 0x0F000F0F00L;
// Now digits is in the form 0xUU00TTHH00 (UU: units digit, TT: tens digit, HH: hundreds digit)
// 0xUU00TTHH00 * (100 * 0x1000000 + 10 * 0x10000 + 1) =
// 0x000000UU00TTHH00 +
// 0x00UU00TTHH000000 * 10 +
// 0xUU00TTHH00000000 * 100
// Now TT * 100 has 2 trailing zeroes and HH * 100 + TT * 10 + UU < 0x400
// This results in our value lies in the bit 32 to 41 of this product
// That was close :)
long absValue = ((digits * 0x640a0001) >>> 32) & 0x3FF;
long value = (absValue ^ signed) - signed;
aggr.min = Math.min(value, aggr.min);
aggr.max = Math.max(value, aggr.max);
aggr.sum += value;
aggr.count++;
return offset + (decimalSepPos >>> 3) + 3;
}
// Tail processing version of the above, do not over-fetch and be simple
private static long parseDataPointTail(Aggregator aggr, MemorySegment data, long offset) {
int point = 0;
boolean negative = false;
if (data.get(ValueLayout.JAVA_BYTE, offset) == '-') {
negative = true;
offset++;
}
for (;; offset++) {
int c = data.get(ValueLayout.JAVA_BYTE, offset);
if (c == '.') {
c = data.get(ValueLayout.JAVA_BYTE, offset + 1);
point = point * 10 + (c - '0');
offset += 3;
break;
}
point = point * 10 + (c - '0');
}
point = negative ? -point : point;
aggr.min = Math.min(point, aggr.min);
aggr.max = Math.max(point, aggr.max);
aggr.sum += point;
aggr.count++;
return offset;
}
// An iteration of the main parse loop, parse some lines starting from offset.
// This requires offset to be the start of a line and there is spare space so
// that we have relative freedom in processing
// It returns the offset of the next line that it needs to be processed
private static long iterate(PoorManMap aggrMap, MemorySegment data, long offset) {
// This method fetches a segment of the file starting from offset and returns after
// finishing processing that segment
var line = ByteVector.fromMemorySegment(BYTE_SPECIES, data, offset, ByteOrder.nativeOrder());
// Find the delimiter ';'
long semicolons = line.compare(VectorOperators.EQ, ';').toLong();
// If we cannot find the delimiter in the current segment, that means the key is
// longer than the segment, fall back to scalar processing
if (semicolons == 0) {
long semicolonPos = BYTE_SPECIES.vectorByteSize();
for (; data.get(ValueLayout.JAVA_BYTE, offset + semicolonPos) != ';'; semicolonPos++) {
}
int hash = line.reinterpretAsInts().lane(0);
var aggr = aggrMap.indexSimple(offset, semicolonPos, hash);
return parseDataPoint(aggr, data, offset + 1 + semicolonPos);
}
long currOffset = offset;
while (true) {
// Process line by line, currOffset is the offset of the current line in
// the file, localOffset is the offset of the current line with respect
// to the start of the iteration segment
int localOffset = (int) (currOffset - offset);
// The key length
long semicolonPos = Long.numberOfTrailingZeros(semicolons) - localOffset;
int hash = data.get(ValueLayout.JAVA_INT_UNALIGNED, currOffset);
if (semicolonPos < Integer.BYTES) {
hash = (byte) hash;
}
// We inline the searching of the value in the hash map
Aggregator aggr;
hash = PoorManMap.rehash(hash);
int bucketMask = aggrMap.nodes.length - 1;
int bucket = hash & bucketMask;
for (;; bucket = (bucket + 1) & bucketMask) {
PoorManMap.PoorManMapNode node = aggrMap.nodes[bucket];
if (node == null) {
aggrMap.size++;
if (aggrMap.size * PoorManMap.R_LOAD_FACTOR > aggrMap.nodes.length) {
aggrMap.grow();
bucketMask = aggrMap.nodes.length - 1;
for (bucket = hash & bucketMask; aggrMap.nodes[bucket] != null; bucket = (bucket + 1) & bucketMask) {
}
}
node = new PoorManMap.PoorManMapNode(data, currOffset, semicolonPos, hash);
aggrMap.nodes[bucket] = node;
aggr = node.aggr;
break;
}
if (node.hash != hash || node.size != semicolonPos) {
continue;
}
// The technique here is to align the key in both vectors so that we can do an
// element-wise comparison and check if all characters match
var nodeKey = ByteVector.fromArray(BYTE_SPECIES, node.data, BYTE_SPECIES.length() - localOffset);
var eqMask = line.compare(VectorOperators.EQ, nodeKey).toLong();
long validMask = (-1L >>> -semicolonPos) << localOffset;
if ((eqMask & validMask) == validMask) {
aggr = node.aggr;
break;
}
}
long nextOffset = parseDataPoint(aggr, data, currOffset + 1 + semicolonPos);
semicolons &= (semicolons - 1);
if (semicolons == 0) {
return nextOffset;
}
currOffset = nextOffset;
}
}
// Process all lines that start in [offset, limit)
private static PoorManMap processFile(MemorySegment data, long offset, long limit) {
var aggrMap = new PoorManMap(data);
// Find the start of a new line
if (offset != 0) {
offset--;
for (; offset < limit;) {
if (data.get(ValueLayout.JAVA_BYTE, offset++) == '\n') {
break;
}
}
}
// If there is no line starting in this segment, just return
if (offset == limit) {
return aggrMap;
}
// The main loop, optimized for speed
while (offset < limit - Math.max(BYTE_SPECIES.vectorByteSize(),
Long.BYTES + 1 + KEY_MAX_SIZE)) {
offset = iterate(aggrMap, data, offset);
}
// Now we are at the tail, just be simple
while (offset < limit) {
long semicolonPos = 0;
for (; data.get(ValueLayout.JAVA_BYTE, offset + semicolonPos) != ';'; semicolonPos++) {
}
int hash;
if (semicolonPos >= Integer.BYTES) {
hash = data.get(ValueLayout.JAVA_INT_UNALIGNED, offset);
}
else {
hash = data.get(ValueLayout.JAVA_BYTE, offset);
}
var aggr = aggrMap.indexSimple(offset, semicolonPos, hash);
offset = parseDataPointTail(aggr, data, offset + 1 + semicolonPos);
}
return aggrMap;
}
public static void main(String[] args) throws InterruptedException, IOException {
int processorCnt = Runtime.getRuntime().availableProcessors();
var res = HashMap.<String, Aggregator> newHashMap(processorCnt);
try (var file = FileChannel.open(Path.of(FILE), StandardOpenOption.READ);
var arena = Arena.ofShared()) {
var data = file.map(MapMode.READ_ONLY, 0, file.size(), arena);
long chunkSize = Math.ceilDiv(data.byteSize(), processorCnt);
var threadList = new Thread[processorCnt];
var resultList = new PoorManMap[processorCnt];
for (int i = 0; i < processorCnt; i++) {
int index = i;
long offset = i * chunkSize;
long limit = Math.min((i + 1) * chunkSize, data.byteSize());
var thread = new Thread(() -> {
resultList[index] = processFile(data, offset, limit);
});
threadList[index] = thread;
thread.start();
}
for (var thread : threadList) {
thread.join();
}
// Collect the results
for (var aggrMap : resultList) {
for (var node : aggrMap.nodes) {
if (node == null) {
continue;
}
byte[] keyData = Arrays.copyOfRange(node.data, BYTE_SPECIES.vectorByteSize(), BYTE_SPECIES.vectorByteSize() + (int) node.size);
String key = new String(keyData, StandardCharsets.UTF_8);
var aggr = node.aggr;
var resAggr = new Aggregator();
var existingAggr = res.putIfAbsent(key, resAggr);
if (existingAggr != null) {
resAggr = existingAggr;
}
resAggr.min = Math.min(resAggr.min, aggr.min);
resAggr.max = Math.max(resAggr.max, aggr.max);
resAggr.sum += aggr.sum;
resAggr.count += aggr.count;
}
}
}
Map<String, ResultRow> measurements = new TreeMap<>();
for (var entry : res.entrySet()) {
String key = entry.getKey();
var aggr = entry.getValue();
measurements.put(key, new ResultRow((double) aggr.min / 10, (double) aggr.sum / (aggr.count * 10), (double) aggr.max / 10));
}
System.out.println(measurements);
}
}