improve speed, thanks to the following improvements: (#550)
* improve speed, thanks to the following improvements: - loop unrolling and eleminating extra calculations - eleminating instance level variable access - quicker equals check, checking long by long chunks instead of bytes - update GraalVM version to the latest * faster equals check * fix equals bug in 10K, more optimizations on equals and calculate hash parts * New solution optimized for Linux/AMD hardware * Optimize solution, try to fix 10K bug on native * Optimize solution, move records to a local field * test timing * revert back accidentally pushed code --------- Co-authored-by: Yavuz Tas <yavuz.tas@ing.com>
This commit is contained in:
Yavuz Tas
GitHub
parent
886f0cdb4d
commit
a82cf2ceb7
@ -15,5 +15,11 @@
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# limitations under the License.
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#
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JAVA_OPTS="-Xms128m -Xmx128m -XX:MaxGCPauseMillis=1 -XX:-AlwaysPreTouch -XX:+UseSerialGC --enable-preview"
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java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_yavuztas
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if [ -f target/CalculateAverage_yavuztas_image ]; then
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echo "Picking up existing native image 'target/CalculateAverage_yavuztas_image', delete the file to select JVM mode." 1>&2
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target/CalculateAverage_yavuztas_image
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else
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JAVA_OPTS="-XX:MaxGCPauseMillis=1 -XX:-AlwaysPreTouch -XX:+UseSerialGC -XX:+TieredCompilation --enable-preview"
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echo "Choosing to run the app in JVM mode as no native image was found, use prepare_yavuztas.sh to generate." 1>&2
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java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_yavuztas
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fi
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@ -16,4 +16,9 @@
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#
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source "$HOME/.sdkman/bin/sdkman-init.sh"
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sdk use java 21.0.1-graal 1>&2
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sdk use java 21.0.2-graal 1>&2
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if [ ! -f target/CalculateAverage_yavuztas_image ]; then
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NATIVE_IMAGE_OPTS="--initialize-at-build-time=dev.morling.onebrc.CalculateAverage_yavuztas --gc=epsilon -O3 -march=native -R:MaxHeapSize=128m -H:-GenLoopSafepoints --enable-preview"
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native-image $NATIVE_IMAGE_OPTS -cp target/average-1.0.0-SNAPSHOT.jar -o target/CalculateAverage_yavuztas_image dev.morling.onebrc.CalculateAverage_yavuztas
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fi
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@ -17,15 +17,16 @@ package dev.morling.onebrc;
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import sun.misc.Unsafe;
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import java.io.IOException;
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import java.lang.foreign.Arena;
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import java.lang.reflect.Field;
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import java.nio.ByteBuffer;
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import java.nio.channels.FileChannel;
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import java.nio.charset.StandardCharsets;
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import java.nio.file.Files;
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import java.nio.file.Path;
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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.TreeMap;
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import java.util.function.Consumer;
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@ -35,8 +36,9 @@ public class CalculateAverage_yavuztas {
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private static final Unsafe UNSAFE = unsafe();
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// Tried all there: MappedByteBuffer, MemorySegment and Unsafe
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// Accessing the memory using Unsafe is still the fastest in my experience
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// I compared all three: MappedByteBuffer, MemorySegment and Unsafe.
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// Accessing the memory using Unsafe is still the fastest in my experience.
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// However, I would never use it in production, single programming error will crash your app.
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private static Unsafe unsafe() {
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try {
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final Field f = Unsafe.class.getDeclaredField("theUnsafe");
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@ -48,296 +50,419 @@ public class CalculateAverage_yavuztas {
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}
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}
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/**
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* Extract bytes from a long
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*/
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private static long partial(long word, int length) {
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final long mask = (~0L) << (length << 3);
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return word & (~mask);
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}
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// Only one object, both for measurements and keys, less object creation in hotpots is always faster
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static class Record {
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private static final class Record {
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// keep memory starting address for each segment
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// since we use Unsafe, this is enough to align and fetch the data
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long segment;
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int start;
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int length;
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int hash;
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private final long start; // memory address of the underlying data
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private final int length;
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private final long word1;
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private final long word2;
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private final long wordLast;
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private final int hash;
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private Record next; // linked list to resolve hash collisions
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private int min = 1000; // calculations over int is faster than double, we convert to double in the end only once
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private int max = -1000;
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private int min; // calculations over int is faster than double, we convert to double in the end only once
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private int max;
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private long sum;
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private long count;
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private int count;
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public Record(long segment, int start, int length, int hash) {
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this.segment = segment;
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public Record(long start, int length, long word1, long word2, long wordLast, int hash, int temp) {
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this.start = start;
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this.length = length;
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this.word1 = word1;
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this.word2 = word2;
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this.wordLast = wordLast;
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this.hash = hash;
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this.min = temp;
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this.max = temp;
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this.sum = temp;
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this.count = 1;
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}
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@Override
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public boolean equals(Object o) {
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final Record record = (Record) o;
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return equals(record.segment, record.start, record.length, record.hash);
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return equals(record.start, record.word1, record.word2, record.wordLast, record.length);
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}
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/**
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* Stateless equals, no Record object needed
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*/
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public boolean equals(long segment, int start, int length, int hash) {
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if (this.length != length || this.hash != hash)
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private static boolean notEquals(long address1, long address2, int step) {
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return UNSAFE.getLong(address1 + step) != UNSAFE.getLong(address2 + step);
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}
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private static boolean equalsComparingLongs(long start1, long start2, int length) {
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// first shortcuts
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if (length < 24)
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return true;
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if (length < 32)
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return !notEquals(start1, start2, 16);
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int step = 24; // starting from 3rd long
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length -= step;
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while (length >= 8) { // scan longs
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if (notEquals(start1, start2, step)) {
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return false;
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}
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length -= 8;
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step += 8; // 8 bytes
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}
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return true;
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}
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private boolean equals(long start, long word1, long word2, long last, int length) {
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if (this.word1 != word1)
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return false;
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if (this.word2 != word2)
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return false;
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int i = 0; // bytes mismatch check
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while (i < this.length
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&& UNSAFE.getByte(this.segment + this.start + i) == UNSAFE.getByte(segment + start + i)) {
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i++;
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}
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return i == this.length;
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}
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@Override
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public int hashCode() {
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return this.hash;
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// equals check is done by comparing longs instead of byte by byte check, this is faster
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return equalsComparingLongs(this.start, start, length) && this.wordLast == last;
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}
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@Override
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public String toString() {
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final byte[] bytes = new byte[this.length];
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int i = 0;
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while (i < this.length) {
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bytes[i] = UNSAFE.getByte(this.segment + this.start + i++);
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}
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UNSAFE.copyMemory(null, this.start, bytes, Unsafe.ARRAY_BYTE_BASE_OFFSET, this.length);
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return new String(bytes, StandardCharsets.UTF_8);
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}
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public Record collect(int temp) {
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this.min = Math.min(this.min, temp);
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this.max = Math.max(this.max, temp);
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private void collect(int temp) {
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if (temp < this.min)
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this.min = temp;
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if (temp > this.max)
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this.max = temp;
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this.sum += temp;
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this.count++;
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return this;
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}
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public void merge(Record other) {
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this.min = Math.min(this.min, other.min);
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this.max = Math.max(this.max, other.max);
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this.sum += other.sum;
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this.count += other.count;
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private void merge(Record that) {
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if (that.min < this.min)
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this.min = that.min;
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if (that.max > this.max)
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this.max = that.max;
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this.sum += that.sum;
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this.count += that.count;
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}
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public String measurements() {
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private String measurements() {
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// here is only executed once for each unique key, so StringBuilder creation doesn't harm
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final StringBuilder sb = new StringBuilder(14);
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sb.append(this.min / 10.0);
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sb.append("/");
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sb.append(round((this.sum / 10.0) / this.count));
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sb.append("/");
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sb.append(this.max / 10.0);
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sb.append(round(this.min)).append("/");
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sb.append(round(1.0 * this.sum / this.count)).append("/");
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sb.append(round(this.max));
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return sb.toString();
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}
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}
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// Inspired by @spullara - customized hashmap on purpose
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// The main difference is we hold only one array instead of two
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static class RecordMap {
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// The main difference is we hold only one array instead of two, fewer objects is faster
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private static final class RecordMap {
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static final int SIZE = 1 << 15; // 32k - bigger bucket size less collisions
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static final int BITMASK = SIZE - 1;
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Record[] keys = new Record[SIZE];
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// Bigger bucket size less collisions, but you have to find a sweet spot otherwise it is becoming slower.
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// Also works good enough for 10K stations
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private static final int SIZE = 1 << 14; // 16kb - enough for 10K
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private static final int BITMASK = SIZE - 1;
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private final Record[] keys = new Record[SIZE];
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static int hashBucket(int hash) {
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// int collision;
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private boolean hasNoRecord(int index) {
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return this.keys[index] == null;
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}
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private Record getRecord(int index) {
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return this.keys[index];
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}
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private static int hashBucket(int hash) {
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hash = hash ^ (hash >>> 16); // naive bit spreading but surprisingly decreases collision :)
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return hash & BITMASK; // fast modulo, to find bucket
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}
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void putAndCollect(long segment, int start, int length, int hash, int temp) {
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int bucket = hashBucket(hash);
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Record existing = this.keys[bucket];
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if (existing == null) {
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this.keys[bucket] = new Record(segment, start, length, hash)
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.collect(temp);
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private void putAndCollect(int hash, int temp, long start, int length, long word1, long word2, long wordLast) {
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final int bucket = hashBucket(hash);
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if (hasNoRecord(bucket)) {
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this.keys[bucket] = new Record(start, length, word1, word2, wordLast, hash, temp);
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return;
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}
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if (!existing.equals(segment, start, length, hash)) {
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// collision, linear probing to find a slot
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while ((existing = this.keys[++bucket & BITMASK]) != null && !existing.equals(segment, start, length, hash)) {
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// can be stuck here if all the buckets are full :(
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// However, since the data set is max 10K (unique) this shouldn't happen
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// So, I'm happily leave here branchless :)
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}
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if (existing == null) {
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this.keys[bucket & BITMASK] = new Record(segment, start, length, hash)
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.collect(temp);
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Record existing = getRecord(bucket);
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if (existing.equals(start, word1, word2, wordLast, length)) {
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existing.collect(temp);
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return;
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}
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existing.collect(temp);
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// collision++;
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// find possible slot by scanning the slot linked list
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while (existing.next != null) {
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if (existing.next.equals(start, word1, word2, wordLast, length)) {
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existing.next.collect(temp);
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return;
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}
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else {
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existing.collect(temp);
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||||
existing = existing.next; // go on to next
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// collision++;
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}
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existing.next = new Record(start, length, word1, word2, wordLast, hash, temp);
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}
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void putOrMerge(Record key) {
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int bucket = hashBucket(key.hash);
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Record existing = this.keys[bucket];
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if (existing == null) {
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private void putOrMerge(Record key) {
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final int bucket = hashBucket(key.hash);
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if (hasNoRecord(bucket)) {
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key.next = null;
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this.keys[bucket] = key;
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||||
return;
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||||
}
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||||
|
||||
if (!existing.equals(key)) {
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||||
// collision, linear probing to find a slot
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||||
while ((existing = this.keys[++bucket & BITMASK]) != null && !existing.equals(key)) {
|
||||
// can be stuck here if all the buckets are full :(
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||||
// However, since the data set is max 10K (unique keys) this shouldn't happen
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||||
// So, I'm happily leave here branchless :)
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||||
}
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||||
if (existing == null) {
|
||||
this.keys[bucket & BITMASK] = key;
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||||
Record existing = getRecord(bucket);
|
||||
if (existing.equals(key)) {
|
||||
existing.merge(key);
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||||
return;
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||||
}
|
||||
existing.merge(key);
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||||
|
||||
// collision++;
|
||||
// find possible slot by scanning the slot linked list
|
||||
while (existing.next != null) {
|
||||
if (existing.next.equals(key)) {
|
||||
existing.next.merge(key);
|
||||
return;
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||||
}
|
||||
else {
|
||||
existing.merge(key);
|
||||
existing = existing.next; // go on to next
|
||||
// collision++;
|
||||
}
|
||||
key.next = null;
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||||
existing.next = key;
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||||
}
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||||
|
||||
void forEach(Consumer<Record> consumer) {
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private void forEach(Consumer<Record> consumer) {
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int pos = 0;
|
||||
Record key;
|
||||
while (pos < this.keys.length) {
|
||||
while (pos < SIZE) {
|
||||
if ((key = this.keys[pos++]) == null) {
|
||||
continue;
|
||||
}
|
||||
Record next = key.next;
|
||||
consumer.accept(key);
|
||||
while (next != null) { // also traverse the records in the collision list
|
||||
final Record tmp = next.next;
|
||||
consumer.accept(next);
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||||
next = tmp;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
void merge(RecordMap other) {
|
||||
private void merge(RecordMap other) {
|
||||
other.forEach(this::putOrMerge);
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
// One actor for one thread, no synchronization
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||||
static class RegionActor {
|
||||
private static final class RegionActor extends Thread {
|
||||
|
||||
final FileChannel channel;
|
||||
final long startPos;
|
||||
final int size;
|
||||
final RecordMap map = new RecordMap();
|
||||
long segmentAddress;
|
||||
int position;
|
||||
Thread runner; // each actor has its own thread
|
||||
private final long startPos; // start of region memory address
|
||||
private final int size;
|
||||
|
||||
public RegionActor(FileChannel channel, long startPos, int size) {
|
||||
this.channel = channel;
|
||||
private final RecordMap map = new RecordMap();
|
||||
|
||||
public RegionActor(long startPos, int size) {
|
||||
this.startPos = startPos;
|
||||
this.size = size;
|
||||
}
|
||||
|
||||
void accumulate() {
|
||||
this.runner = new Thread(() -> {
|
||||
try {
|
||||
// get the segment memory address, this is the only thing we need for Unsafe
|
||||
this.segmentAddress = this.channel.map(FileChannel.MapMode.READ_ONLY, this.startPos, this.size, Arena.global()).address();
|
||||
}
|
||||
catch (IOException e) {
|
||||
// no-op - skip intentionally, no handling for the purpose of this challenge
|
||||
private static long getWord(long address) {
|
||||
return UNSAFE.getLong(address);
|
||||
}
|
||||
|
||||
int start;
|
||||
int keyHash;
|
||||
int length;
|
||||
while (this.position < this.size) {
|
||||
byte b;
|
||||
start = this.position; // save line start position
|
||||
keyHash = UNSAFE.getByte(this.segmentAddress + this.position++); // first byte is guaranteed not to be ';'
|
||||
length = 1; // min key length
|
||||
while ((b = UNSAFE.getByte(this.segmentAddress + this.position++)) != ';') { // read until semicolon
|
||||
keyHash = calculateHash(keyHash, b); // calculate key hash ahead, eleminates one more loop later
|
||||
length++;
|
||||
// hasvalue & haszero
|
||||
// adapted from https://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord
|
||||
private static long hasSemicolon(long word) {
|
||||
// semicolon pattern
|
||||
final long hasVal = word ^ 0x3B3B3B3B3B3B3B3BL; // hasvalue
|
||||
return ((hasVal - 0x0101010101010101L) & ~hasVal & 0x8080808080808080L); // haszero
|
||||
}
|
||||
|
||||
final int temp = readTemperature();
|
||||
this.map.putAndCollect(this.segmentAddress, start, length, keyHash, temp);
|
||||
|
||||
this.position++; // skip linebreak
|
||||
}
|
||||
});
|
||||
this.runner.start();
|
||||
private static int semicolonPos(long hasVal) {
|
||||
return Long.numberOfTrailingZeros(hasVal) >>> 3;
|
||||
}
|
||||
|
||||
static int calculateHash(int hash, int b) {
|
||||
return 31 * hash + b;
|
||||
private static int decimalPos(long numberWord) {
|
||||
return Long.numberOfTrailingZeros(~numberWord & 0x10101000);
|
||||
}
|
||||
|
||||
// 1. Inspired by @yemreinci - Reading temparature value without Double.parse
|
||||
// 2. Inspired by @obourgain - Fetching first 4 bytes ahead, then masking
|
||||
int readTemperature() {
|
||||
int temp = 0;
|
||||
// read 4 bytes ahead
|
||||
final int first4 = UNSAFE.getInt(this.segmentAddress + this.position);
|
||||
this.position += 3;
|
||||
private static final int MAX_INNER_LOOP_SIZE = 11;
|
||||
|
||||
final byte b1 = (byte) first4; // first byte
|
||||
final byte b2 = (byte) ((first4 >> 8) & 0xFF); // second byte
|
||||
final byte b3 = (byte) ((first4 >> 16) & 0xFF); // third byte
|
||||
if (b1 == '-') {
|
||||
if (b3 == '.') {
|
||||
temp -= 10 * (b2 - '0') + (byte) ((first4 >> 24) & 0xFF) - '0'; // fourth byte
|
||||
this.position++;
|
||||
@Override
|
||||
public void run() {
|
||||
long pointer = this.startPos;
|
||||
final long size = pointer + this.size;
|
||||
while (pointer < size) { // line start
|
||||
long hash = 0; // reset hash
|
||||
long s; // semicolon check word
|
||||
final int pos; // semicolon position
|
||||
long word1 = getWord(pointer);
|
||||
if ((s = hasSemicolon(word1)) != 0) {
|
||||
pos = semicolonPos(s);
|
||||
// read temparature
|
||||
final long numberWord = getWord(pointer + pos + 1);
|
||||
final int decimalPos = decimalPos(numberWord);
|
||||
final int temp = convertIntoNumber(decimalPos, numberWord);
|
||||
|
||||
word1 = partial(word1, pos); // last word
|
||||
this.map.putAndCollect(completeHash(hash, word1), temp, pointer, pos, word1, 0, 0);
|
||||
|
||||
pointer += pos + (decimalPos >>> 3) + 4;
|
||||
}
|
||||
else {
|
||||
this.position++; // skip dot
|
||||
temp -= 100 * (b2 - '0') + 10 * (b3 - '0') + UNSAFE.getByte(this.segmentAddress + this.position++) - '0'; // fifth byte
|
||||
}
|
||||
long word2 = getWord(pointer + 8);
|
||||
if ((s = hasSemicolon(word2)) != 0) {
|
||||
pos = semicolonPos(s);
|
||||
// read temparature
|
||||
final int length = pos + 8;
|
||||
final long numberWord = getWord(pointer + length + 1);
|
||||
final int decimalPos = decimalPos(numberWord);
|
||||
final int temp = convertIntoNumber(decimalPos, numberWord);
|
||||
|
||||
word2 = partial(word2, pos); // last word
|
||||
this.map.putAndCollect(completeHash(hash, word1, word2), temp, pointer, length, word1, word2, 0);
|
||||
|
||||
pointer += length + (decimalPos >>> 3) + 4; // seek to the line end
|
||||
}
|
||||
else {
|
||||
if (b2 == '.') {
|
||||
temp = 10 * (b1 - '0') + b3 - '0';
|
||||
long word = 0;
|
||||
int length = 16;
|
||||
hash = appendHash(hash, word1, word2);
|
||||
// Let the compiler know the loop size ahead
|
||||
// Then it's automatically unrolled
|
||||
// Max key length is 13 longs, 2 we've read before, 11 left
|
||||
for (int i = 0; i < MAX_INNER_LOOP_SIZE; i++) {
|
||||
if ((s = hasSemicolon((word = getWord(pointer + length)))) != 0) {
|
||||
break;
|
||||
}
|
||||
hash = appendHash(hash, word);
|
||||
length += 8;
|
||||
}
|
||||
|
||||
pos = semicolonPos(s);
|
||||
length += pos;
|
||||
// read temparature
|
||||
final long numberWord = getWord(pointer + length + 1);
|
||||
final int decimalPos = decimalPos(numberWord);
|
||||
final int temp = convertIntoNumber(decimalPos, numberWord);
|
||||
|
||||
word = partial(word, pos); // last word
|
||||
this.map.putAndCollect(completeHash(hash, word), temp, pointer, length, word1, word2, word);
|
||||
|
||||
pointer += length + (decimalPos >>> 3) + 4; // seek to the line end
|
||||
}
|
||||
}
|
||||
else {
|
||||
temp = 100 * (b1 - '0') + 10 * (b2 - '0') + (byte) ((first4 >> 24) & 0xFF) - '0'; // fourth byte
|
||||
this.position++;
|
||||
}
|
||||
}
|
||||
|
||||
return temp;
|
||||
// Hashes are calculated by a Mersenne Prime (1 << 7) -1
|
||||
// This is faster than multiplication in some machines
|
||||
private static long appendHash(long hash, long word) {
|
||||
return (hash << 7) - hash + word;
|
||||
}
|
||||
|
||||
private static long appendHash(long hash, long word1, long word2) {
|
||||
hash = (hash << 7) - hash + word1;
|
||||
return (hash << 7) - hash + word2;
|
||||
}
|
||||
|
||||
private static int completeHash(long hash, long partial) {
|
||||
hash = (hash << 7) - hash + partial;
|
||||
return (int) (hash ^ (hash >>> 25));
|
||||
}
|
||||
|
||||
private static int completeHash(long hash, long word1, long word2) {
|
||||
hash = (hash << 7) - hash + word1;
|
||||
hash = (hash << 7) - hash + word2;
|
||||
return (int) hash ^ (int) (hash >>> 25);
|
||||
}
|
||||
|
||||
// Credits to @merrykitty. Magical solution to parse temparature values branchless!
|
||||
// Taken as without modification, comments belong to @merrykitty
|
||||
private static int convertIntoNumber(int decimalSepPos, long numberWord) {
|
||||
final int shift = 28 - decimalSepPos;
|
||||
// signed is -1 if negative, 0 otherwise
|
||||
final long signed = (~numberWord << 59) >> 63;
|
||||
final long designMask = ~(signed & 0xFF);
|
||||
// Align the number to a specific position and transform the ascii code
|
||||
// to actual digit value in each byte
|
||||
final long digits = ((numberWord & 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 :)
|
||||
final long absValue = ((digits * 0x640a0001) >>> 32) & 0x3FF;
|
||||
final long value = (absValue ^ signed) - signed;
|
||||
return (int) value;
|
||||
}
|
||||
|
||||
/**
|
||||
* blocks until the map is fully collected
|
||||
*/
|
||||
RecordMap get() throws InterruptedException {
|
||||
this.runner.join();
|
||||
private RecordMap get() throws InterruptedException {
|
||||
join();
|
||||
return this.map;
|
||||
}
|
||||
}
|
||||
|
||||
private static double round(double value) {
|
||||
return Math.round(value * 10.0) / 10.0;
|
||||
return Math.round(value) / 10.0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Scans the given buffer to the left
|
||||
*/
|
||||
private static long findClosestLineEnd(long start, int size, FileChannel channel) throws IOException {
|
||||
final long position = start + size;
|
||||
final long left = Math.max(position - 101, 0);
|
||||
final ByteBuffer buffer = ByteBuffer.allocate(101); // enough size to find at least one '\n'
|
||||
if (channel.read(buffer.clear(), left) != -1) {
|
||||
int bufferPos = buffer.position() - 1;
|
||||
while (buffer.get(bufferPos) != '\n') {
|
||||
bufferPos--;
|
||||
private static long findClosestLineEnd(long start, int size) {
|
||||
long position = start + size;
|
||||
while (UNSAFE.getByte(--position) != '\n') {
|
||||
// read until a linebreak
|
||||
size--;
|
||||
}
|
||||
}
|
||||
return size;
|
||||
}
|
||||
|
||||
public static void main(String[] args) throws IOException, InterruptedException {
|
||||
private static boolean isWorkerProcess(String[] args) {
|
||||
return Arrays.asList(args).contains("--worker");
|
||||
}
|
||||
|
||||
var concurrency = Runtime.getRuntime().availableProcessors();
|
||||
private static void runAsWorker() throws Exception {
|
||||
final ProcessHandle.Info info = ProcessHandle.current().info();
|
||||
final List<String> commands = new ArrayList<>();
|
||||
info.command().ifPresent(commands::add);
|
||||
info.arguments().ifPresent(args -> commands.addAll(Arrays.asList(args)));
|
||||
commands.add("--worker");
|
||||
|
||||
new ProcessBuilder()
|
||||
.command(commands)
|
||||
.start()
|
||||
.getInputStream()
|
||||
.transferTo(System.out);
|
||||
}
|
||||
|
||||
public static void main(String[] args) throws Exception {
|
||||
|
||||
// Dased on @thomaswue's idea, to cut unmapping delay.
|
||||
// Strangely, unmapping delay doesn't occur on macOS/M1 however in Linux/AMD it's substantial - ~200ms
|
||||
if (!isWorkerProcess(args)) {
|
||||
runAsWorker();
|
||||
return;
|
||||
}
|
||||
|
||||
var concurrency = 2 * Runtime.getRuntime().availableProcessors();
|
||||
final long fileSize = Files.size(FILE);
|
||||
long regionSize = fileSize / concurrency;
|
||||
|
||||
@ -353,30 +478,36 @@ public class CalculateAverage_yavuztas {
|
||||
|
||||
long startPos = 0;
|
||||
final FileChannel channel = (FileChannel) Files.newByteChannel(FILE, StandardOpenOption.READ);
|
||||
// get the memory address, this is the only thing we need for Unsafe
|
||||
final long memoryAddress = channel.map(FileChannel.MapMode.READ_ONLY, startPos, fileSize, Arena.global()).address();
|
||||
|
||||
final RegionActor[] actors = new RegionActor[concurrency];
|
||||
for (int i = 0; i < concurrency; i++) {
|
||||
// calculate boundaries
|
||||
long maxSize = (startPos + regionSize > fileSize) ? fileSize - startPos : regionSize;
|
||||
// shift position to back until we find a linebreak
|
||||
maxSize = findClosestLineEnd(startPos, (int) maxSize, channel);
|
||||
maxSize = findClosestLineEnd(memoryAddress + startPos, (int) maxSize);
|
||||
|
||||
final RegionActor region = (actors[i] = new RegionActor(channel, startPos, (int) maxSize));
|
||||
region.accumulate();
|
||||
final RegionActor region = (actors[i] = new RegionActor(memoryAddress + startPos, (int) maxSize));
|
||||
region.start(); // start processing
|
||||
|
||||
startPos += maxSize;
|
||||
}
|
||||
|
||||
final RecordMap output = new RecordMap(); // output to merge all regions
|
||||
final RecordMap output = new RecordMap(); // output to merge all records
|
||||
for (RegionActor actor : actors) {
|
||||
final RecordMap partial = actor.get(); // blocks until get the result
|
||||
output.merge(partial);
|
||||
// System.out.println("collisions: " + partial.collision);
|
||||
}
|
||||
|
||||
// sort and print the result
|
||||
final TreeMap<String, String> sorted = new TreeMap<>();
|
||||
output.forEach(key -> sorted.put(key.toString(), key.measurements()));
|
||||
output.forEach(key -> {
|
||||
sorted.put(key.toString(), key.measurements());
|
||||
});
|
||||
System.out.println(sorted);
|
||||
|
||||
System.out.close(); // closing the stream will trigger the main process to pick up the output early
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user