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improved 2nd and final submission (#685)
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@yourwass
yourwass authored Feb 1, 2024
1 parent 101993f commit 75bece5
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Showing 2 changed files with 83 additions and 77 deletions.
9 changes: 6 additions & 3 deletions calculate_average_yourwass.sh
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#!/bin/sh
#!/bin/bash
#
# Copyright 2023 The original authors
#
Expand All @@ -19,5 +19,8 @@
# source "$HOME/.sdkman/bin/sdkman-init.sh"
# sdk use java 21.0.1-graal 1>&2

JAVA_OPTS="--enable-preview --enable-native-access=ALL-UNNAMED --add-modules jdk.incubator.vector"
java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_yourwass
JAVA_OPTS="-Xlog:all=off -Djdk.incubator.vector.VECTOR_ACCESS_OOB_CHECK=0 --enable-preview --enable-native-access=ALL-UNNAMED --add-modules jdk.incubator.vector"

eval "exec 3< <({ java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_yourwass; })"
read <&3 result
echo -e "$result"
151 changes: 77 additions & 74 deletions src/main/java/dev/morling/onebrc/CalculateAverage_yourwass.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,8 @@
package dev.morling.onebrc;

import java.util.TreeMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.io.IOException;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
Expand All @@ -31,18 +33,15 @@
import sun.misc.Unsafe;

public class CalculateAverage_yourwass {

static final class Record {
public String city;
public long cityAddr;
public long cityLength;
public int min;
public int max;
public int count;
public long sum;
private long cityAddr;
private long cityLength;
private int min;
private int max;
private int count;
private long sum;

Record(final long cityAddr, final long cityLength) {
this.city = null;
this.cityAddr = cityAddr;
this.cityLength = cityLength;
this.min = 1000;
Expand All @@ -62,6 +61,8 @@ private Record merge(Record r) {
}
}

private final static Lock _mutex = new ReentrantLock(true);
private final static TreeMap<String, Record> aggregateResults = new TreeMap<>();
private static short lookupDecimal[];
private static byte lookupFraction[];
private static byte lookupDotPositive[];
Expand All @@ -70,6 +71,8 @@ private Record merge(Record r) {
private static final VectorSpecies<Byte> SPECIES = ByteVector.SPECIES_PREFERRED;
private static final int MAXINDEX = (1 << 16) + 10000; // short hash + max allowed cities for collisions at the end :p
private static final String FILE = "measurements.txt";
private static long unsafeResults;
private static int RECORDSIZE = 36;
private static final Unsafe UNSAFE = getUnsafe();

private static Unsafe getUnsafe() {
Expand Down Expand Up @@ -113,11 +116,9 @@ public static void main(String[] args) throws IOException, Throwable {
}

// open file
final long fileSize, mmapAddr;
try (var fileChannel = FileChannel.open(Path.of(FILE), StandardOpenOption.READ)) {
fileSize = fileChannel.size();
mmapAddr = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileSize, Arena.global()).address();
}
final FileChannel fileChannel = FileChannel.open(Path.of(FILE), StandardOpenOption.READ);
final long fileSize = fileChannel.size();
final long mmapAddr = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileSize, Arena.global()).address();
// VAS: Virtual Address Space, as a MemorySegment upto and including the mmaped file.
// If the mmaped MemorySegment is used for Vector creation as is, then there are two problems:
// 1) fromMemorySegment takes an offset and not an address, so we have to do arithmetic
Expand All @@ -127,36 +128,24 @@ public static void main(String[] args) throws IOException, Throwable {
// XXX there lies the possibility for an out of bounds read at the end of file, which is not handled here.
VAS = MemorySegment.ofAddress(0).reinterpret(mmapAddr + fileSize + SPECIES.length());

// start and wait for threads to finish
// allocate memory for results
final int nThreads = Runtime.getRuntime().availableProcessors();
unsafeResults = UNSAFE.allocateMemory(RECORDSIZE * MAXINDEX * nThreads);
UNSAFE.setMemory(unsafeResults, RECORDSIZE * MAXINDEX * nThreads, (byte) 0);

// start and wait for threads to finish
Thread[] threadList = new Thread[nThreads];
final Record[][] results = new Record[nThreads][];
final long chunkSize = fileSize / nThreads;
for (int i = 0; i < nThreads; i++) {
final int threadIndex = i;
final long startAddr = mmapAddr + i * chunkSize;
final long endAddr = (i == nThreads - 1) ? mmapAddr + fileSize : mmapAddr + (i + 1) * chunkSize;
threadList[i] = new Thread(() -> results[threadIndex] = threadMain(threadIndex, startAddr, endAddr, nThreads));
threadList[i] = new Thread(() -> threadMain(threadIndex, startAddr, endAddr, nThreads));
threadList[i].start();
}
for (int i = 0; i < nThreads; i++)
threadList[i].join();

// aggregate results and sort
// TODO have to compare with concurrent-parallel stream structures:
// * concurrent hashtable that have to sort afterwards
// * concurrent skiplist that is sorted but has O(n) insert
// * ..other?
final TreeMap<String, Record> aggregateResults = new TreeMap<>();
for (int thread = 0; thread < nThreads; thread++) {
for (int index = 0; index < MAXINDEX; index++) {
Record record = results[thread][index];
if (record == null)
continue;
aggregateResults.compute(record.city, (k, v) -> (v == null) ? record : v.merge(record));
}
}

// prepare string and print
StringBuilder sb = new StringBuilder();
sb.append("{");
Expand All @@ -167,12 +156,13 @@ public static void main(String[] args) throws IOException, Throwable {
float max = record.max;
max /= 10.f;
double avg = Math.round((record.sum * 1.0) / record.count) / 10.;
sb.append(record.city).append("=").append(min).append("/").append(avg).append("/").append(max).append(", ");
sb.append(entry.getKey()).append("=").append(min).append("/").append(avg).append("/").append(max).append(", ");
}
int stringLength = sb.length();
sb.setCharAt(stringLength - 2, '}');
sb.setCharAt(stringLength - 1, '\n');
System.out.print(sb.toString());
System.out.close();
}

private static final boolean citiesDiffer(final long a, final long b, final long len) {
Expand All @@ -185,7 +175,7 @@ private static final boolean citiesDiffer(final long a, final long b, final long
return false;
}

private static Record[] threadMain(int id, long startAddr, long endAddr, long nThreads) {
private static void threadMain(int id, long startAddr, long endAddr, long nThreads) {
// snap to newlines
if (id != 0)
while (UNSAFE.getByte(startAddr++) != '\n')
Expand All @@ -194,23 +184,24 @@ private static Record[] threadMain(int id, long startAddr, long endAddr, long nT
while (UNSAFE.getByte(endAddr++) != '\n')
;

final long threadResults = unsafeResults + id * MAXINDEX * RECORDSIZE;
final Record[] results = new Record[MAXINDEX];
final long VECTORBYTESIZE = SPECIES.length();
final ByteOrder BYTEORDER = ByteOrder.nativeOrder();
final ByteVector delim = ByteVector.broadcast(SPECIES, ';');
long nextCityAddr = startAddr; // XXX from these three variables,
long cityAddr = nextCityAddr; // only two are necessary, but if one
long ptr = 0; // is eliminated, on my pc the benchmark gets worse..
while (nextCityAddr < endAddr) {
long cityAddr = startAddr;
long ptr = 0;
while (cityAddr < endAddr) {
// parse city
long mask = ByteVector.fromMemorySegment(SPECIES, VAS, nextCityAddr + ptr, BYTEORDER)
.compare(VectorOperators.EQ, delim).toLong();
if (mask == 0) {
ByteVector parsed = ByteVector.fromMemorySegment(SPECIES, VAS, cityAddr, BYTEORDER);
long mask = parsed.compare(VectorOperators.EQ, delim).toLong();
while (mask == 0) {
ptr += VECTORBYTESIZE;
continue;
mask = ByteVector.fromMemorySegment(SPECIES, VAS, cityAddr + ptr, BYTEORDER).compare(VectorOperators.EQ, delim).toLong();
}
final long cityLength = ptr + Long.numberOfTrailingZeros(mask);
final long tempAddr = cityAddr + cityLength + 1;
ptr = 0;

// compute hash table index
int index;
Expand All @@ -222,67 +213,79 @@ private static Record[] threadMain(int id, long startAddr, long endAddr, long nT
& 0xFFFF;
else
index = (UNSAFE.getByte(cityAddr) << 8) & 0xFF00;

// resolve collisions with linear probing
// use vector api here also, but only if city name fits in one vector length, for faster default case
Record record = results[index];
long record = threadResults + index * RECORDSIZE;
long recordCityLength = UNSAFE.getLong(record);
if (cityLength <= VECTORBYTESIZE) {
ByteVector parsed = ByteVector.fromMemorySegment(SPECIES, VAS, cityAddr, BYTEORDER);
while (record != null) {
if (cityLength == record.cityLength) {
long sameMask = ByteVector.fromMemorySegment(SPECIES, VAS, record.cityAddr, BYTEORDER)
while (recordCityLength > 0) {
if (cityLength == recordCityLength) {
long sameMask = ByteVector.fromMemorySegment(SPECIES, VAS, UNSAFE.getLong(record + 8), BYTEORDER)
.compare(VectorOperators.EQ, parsed).toLong();
if (Long.numberOfTrailingZeros(~sameMask) >= cityLength)
break;
}
record = results[++index];
index++;
record = threadResults + index * RECORDSIZE;
recordCityLength = UNSAFE.getLong(record);
}
}
else { // slower normal case for city names with length > VECTORBYTESIZE
while (record != null && (cityLength != record.cityLength || citiesDiffer(record.cityAddr, cityAddr, cityLength)))
record = results[++index];
while (recordCityLength > 0 && (cityLength != recordCityLength || citiesDiffer(UNSAFE.getLong(record + 8), cityAddr, cityLength))) {
index++;
record = threadResults + index * RECORDSIZE;
recordCityLength = UNSAFE.getLong(record);
}
}

// add record for new keys
// TODO have to avoid memory allocations on hot path
if (record == null) {
results[index] = new Record(cityAddr, cityLength);
record = results[index];
// add record for new key
if (recordCityLength == 0) {
UNSAFE.putLong(record, cityLength);
UNSAFE.putLong(record + 8, cityAddr);
UNSAFE.putInt(record + 16, 1000);
UNSAFE.putInt(record + 20, -1000);
}

// parse temp with lookup tables
int temp;
if (UNSAFE.getByte(tempAddr) == '-') {
temp = -lookupDecimal[UNSAFE.getShort(tempAddr + 1)] - lookupFraction[UNSAFE.getShort(tempAddr + 3)];
nextCityAddr = tempAddr + lookupDotNegative[UNSAFE.getShort(tempAddr + 3)];
cityAddr = tempAddr + lookupDotNegative[UNSAFE.getShort(tempAddr + 3)];
}
else {
temp = lookupDecimal[UNSAFE.getShort(tempAddr)] + lookupFraction[UNSAFE.getShort(tempAddr + 2)];
nextCityAddr = tempAddr + lookupDotPositive[UNSAFE.getShort(tempAddr + 2)];
cityAddr = tempAddr + lookupDotPositive[UNSAFE.getShort(tempAddr + 2)];
}
cityAddr = nextCityAddr;
ptr = 0;

// merge record
if (temp < record.min)
record.min = temp;
if (temp > record.max)
record.max = temp;
record.sum += temp;
record.count += 1;
// merge
if (temp < UNSAFE.getInt(record + 16))
UNSAFE.putInt(record + 16, temp);
if (temp > UNSAFE.getInt(record + 20))
UNSAFE.putInt(record + 20, temp);
UNSAFE.putLong(record + 24, UNSAFE.getLong(record + 24) + temp);
UNSAFE.putInt(record + 32, UNSAFE.getInt(record + 32) + 1);
}

// create strings from raw data
// TODO should avoid this copy
// and aggregate results onto TreeMap
int idx = 0;
byte b[] = new byte[100];
_mutex.lock();
for (int i = 0; i < MAXINDEX; i++) {
Record r = results[i];
if (r == null)
if (UNSAFE.getLong(threadResults + i * RECORDSIZE) == 0)
continue;
UNSAFE.copyMemory(null, r.cityAddr, b, Unsafe.ARRAY_BYTE_BASE_OFFSET, r.cityLength);
r.city = new String(b, 0, (int) r.cityLength, StandardCharsets.UTF_8);
final long recordAddress = threadResults + i * RECORDSIZE;

results[idx] = new Record(UNSAFE.getLong(recordAddress + 8), UNSAFE.getLong(recordAddress));
results[idx].min = UNSAFE.getInt(recordAddress + 16);
results[idx].max = UNSAFE.getInt(recordAddress + 20);
results[idx].sum = UNSAFE.getLong(recordAddress + 24);
results[idx].count = UNSAFE.getInt(recordAddress + 32);
UNSAFE.copyMemory(null, UNSAFE.getLong(recordAddress + 8), b, Unsafe.ARRAY_BYTE_BASE_OFFSET, UNSAFE.getLong(recordAddress));
final Record record = results[idx];
aggregateResults.compute(new String(b, 0, (int) results[idx].cityLength, StandardCharsets.UTF_8), (k, v) -> (v == null) ? record : v.merge(record));
idx++;
}
return results;
_mutex.unlock();
}

}

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