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-rw-r--r--calculate_average_ddimtirov.sh5
-rw-r--r--src/main/java/dev/morling/onebrc/CalculateAverage_ddimtirov.java126
2 files changed, 70 insertions, 61 deletions
diff --git a/calculate_average_ddimtirov.sh b/calculate_average_ddimtirov.sh
index 26fb652..94a1981 100644
--- a/calculate_average_ddimtirov.sh
+++ b/calculate_average_ddimtirov.sh
@@ -15,6 +15,7 @@
# limitations under the License.
#
-
-JAVA_OPTS="-XX:+UseParallelGC"
+# --enable-preview to use the new memory mapped segments
+# We don't allocate much, so just give it 1G heap and turn off GC; the AlwaysPreTouch was suggested by the ergonomics
+JAVA_OPTS="--enable-preview -Xms1g -Xmx1g -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -XX:+AlwaysPreTouch"
time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_ddimtirov
diff --git a/src/main/java/dev/morling/onebrc/CalculateAverage_ddimtirov.java b/src/main/java/dev/morling/onebrc/CalculateAverage_ddimtirov.java
index 5a9261b..7f5ac50 100644
--- a/src/main/java/dev/morling/onebrc/CalculateAverage_ddimtirov.java
+++ b/src/main/java/dev/morling/onebrc/CalculateAverage_ddimtirov.java
@@ -15,9 +15,10 @@
*/
package dev.morling.onebrc;
-
import java.io.*;
-import java.nio.MappedByteBuffer;
+import java.lang.foreign.Arena;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.ValueLayout;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
@@ -47,15 +48,16 @@ public class CalculateAverage_ddimtirov {
var start = Instant.now();
var desiredSegmentsCount = Runtime.getRuntime().availableProcessors();
- var segments = FileSegment.forFile(path, desiredSegmentsCount);
+ var fileSegments = FileSegment.forFile(path, desiredSegmentsCount);
- var trackers = segments.stream().parallel().map(segment -> {
+ var trackers = fileSegments.stream().parallel().map(fileSegment -> {
try (var fileChannel = (FileChannel) Files.newByteChannel(path, StandardOpenOption.READ)) {
var tracker = new Tracker();
- var segmentBuffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, segment.start(), segment.size());
- tracker.processSegment(segmentBuffer, segment.end());
+ var memorySegment = fileChannel.map(FileChannel.MapMode.READ_ONLY, fileSegment.start(), fileSegment.size(), Arena.ofConfined());
+ tracker.processSegment(memorySegment);
return tracker;
- } catch (IOException e) {
+ }
+ catch (IOException e) {
throw new RuntimeException(e);
}
}).toList();
@@ -63,27 +65,27 @@ public class CalculateAverage_ddimtirov {
var result = summarizeTrackers(trackers);
System.out.println(result);
- //noinspection ConstantValue
- if (start!=null) System.err.println(Duration.between(start, Instant.now()));
- assert Files.readAllLines(Path.of("expected_result.txt")).getFirst().equals(result);
+ // noinspection ConstantValue
+ if (start != null)
+ System.err.println(Duration.between(start, Instant.now()));
+ assert Files.readAllLines(Path.of("measurements_result.txt")).getFirst().equals(result);
}
-
- record FileSegment(long start, long end) {
- public long size() { return end() - start(); }
-
+ record FileSegment(long start, long size) {
public static List<FileSegment> forFile(Path file, int desiredSegmentsCount) throws IOException {
try (var raf = new RandomAccessFile(file.toFile(), "r")) {
- List<FileSegment> segments = new ArrayList<>();
- long fileSize = raf.length();
- long segmentSize = fileSize / desiredSegmentsCount;
+ var segments = new ArrayList<FileSegment>();
+ var fileSize = raf.length();
+ var segmentSize = fileSize / desiredSegmentsCount;
for (int segmentIdx = 0; segmentIdx < desiredSegmentsCount; segmentIdx++) {
- long segStart = segmentIdx * segmentSize;
- long segEnd = (segmentIdx == desiredSegmentsCount - 1) ? fileSize : segStart + segmentSize;
+ var segStart = segmentIdx * segmentSize;
+ var segEnd = (segmentIdx == desiredSegmentsCount - 1) ? fileSize : segStart + segmentSize;
segStart = findSegmentBoundary(raf, segmentIdx, 0, segStart, segEnd);
segEnd = findSegmentBoundary(raf, segmentIdx, desiredSegmentsCount - 1, segEnd, fileSize);
- segments.add(new FileSegment(segStart, segEnd));
+ var segSize = segEnd - segStart;
+
+ segments.add(new FileSegment(segStart, segSize));
}
return segments;
}
@@ -103,28 +105,33 @@ public class CalculateAverage_ddimtirov {
private static String summarizeTrackers(List<Tracker> trackers) {
var result = new TreeMap<String, String>();
- for (int i = 0; i < HASH_NO_CLASH_MODULUS; i++) {
+ for (var i = 0; i < HASH_NO_CLASH_MODULUS; i++) {
String name = null;
- int min = Integer.MAX_VALUE;
- int max = Integer.MIN_VALUE;
- long sum = 0;
- long count = 0;
+ var min = Integer.MAX_VALUE;
+ var max = Integer.MIN_VALUE;
+ var sum = 0L;
+ var count = 0L;
for (Tracker tracker : trackers) {
- if (tracker.names[i]==null) continue;
- if (name==null) name = tracker.names[i];
-
- var minn = tracker.minMaxCount[i*3];
- var maxx = tracker.minMaxCount[i*3+1];
- if (minn<min) min = minn;
- if (maxx>max) max = maxx;
- count += tracker.minMaxCount[i*3+2];
+ if (tracker.names[i] == null)
+ continue;
+ if (name == null)
+ name = tracker.names[i];
+
+ var minn = tracker.minMaxCount[i * 3];
+ var maxx = tracker.minMaxCount[i * 3 + 1];
+ if (minn < min)
+ min = minn;
+ if (maxx > max)
+ max = maxx;
+ count += tracker.minMaxCount[i * 3 + 2];
sum += tracker.sums[i];
}
- if (name==null) continue;
+ if (name == null)
+ continue;
var mean = Math.round((double) sum / count) / 10.0;
- result.put(name, (min/10.0) + "/" + mean + "/" + (max/10.0));
+ result.put(name, (min / 10.0) + "/" + mean + "/" + (max / 10.0));
}
return result.toString();
}
@@ -133,51 +140,50 @@ public class CalculateAverage_ddimtirov {
private final int[] minMaxCount = new int[HASH_NO_CLASH_MODULUS * 3];
private final long[] sums = new long[HASH_NO_CLASH_MODULUS];
private final String[] names = new String[HASH_NO_CLASH_MODULUS];
- private final byte[] nameThreadLocal = new byte[64];
- private void processSegment(MappedByteBuffer segmentBuffer, long segmentEnd) {
- int startLine;
- int limit = segmentBuffer.limit();
- while ((startLine = segmentBuffer.position()) < limit) {
- int pos = startLine;
+ private void processSegment(MemorySegment memory) {
+ int position = 0;
+ long limit = memory.byteSize();
+ while (position < limit) {
+ int pos = position;
byte b;
int nameLength = 0, nameHash = 0;
- while (pos != segmentEnd && (b = segmentBuffer.get(pos++)) != ';') {
- nameHash = nameHash*31 + b;
+ while ((b = memory.get(ValueLayout.JAVA_BYTE, pos++)) != ';') {
+ nameHash = nameHash * 31 + b;
nameLength++;
}
int temperature = 0, sign = 1;
- outer:
- while (pos != segmentEnd && (b = segmentBuffer.get(pos++)) != '\n') {
+ outer: while ((b = memory.get(ValueLayout.JAVA_BYTE, pos++)) != '\n') {
switch (b) {
- case '\r' :
+ case '\r':
pos++;
break outer;
- case '.' :
+ case '.':
break;
- case '-' :
+ case '-':
sign = -1;
break;
- default :
+ default:
var digit = b - '0';
assert digit >= 0 && digit <= 9;
temperature = 10 * temperature + digit;
}
}
- processLine(nameHash, segmentBuffer, startLine, nameLength, temperature * sign);
- segmentBuffer.position(pos);
+ processLine(nameHash, memory, position, nameLength, temperature * sign);
+ position = pos;
}
}
- public void processLine(int nameHash, MappedByteBuffer buffer, int nameOffset, int nameLength, int temperature) {
+ public void processLine(int nameHash, MemorySegment buffer, int nameOffset, int nameLength, int temperature) {
var i = Math.abs(nameHash) % HASH_NO_CLASH_MODULUS;
- if (names[i]==null) {
+ if (names[i] == null) {
names[i] = parseName(buffer, nameOffset, nameLength);
- } else {
+ }
+ else {
assert parseName(buffer, nameOffset, nameLength).equals(names[i]) : parseName(buffer, nameOffset, nameLength) + "!=" + names[i];
}
@@ -186,15 +192,17 @@ public class CalculateAverage_ddimtirov {
int mmcIndex = i * 3;
var min = minMaxCount[mmcIndex + OFFSET_MIN];
var max = minMaxCount[mmcIndex + OFFSET_MAX];
- if (temperature < min) minMaxCount[mmcIndex + OFFSET_MIN] = temperature;
- if (temperature > max) minMaxCount[mmcIndex + OFFSET_MAX] = temperature;
+ if (temperature < min)
+ minMaxCount[mmcIndex + OFFSET_MIN] = temperature;
+ if (temperature > max)
+ minMaxCount[mmcIndex + OFFSET_MAX] = temperature;
minMaxCount[mmcIndex + OFFSET_COUNT]++;
}
- private String parseName(MappedByteBuffer buffer, int nameOffset, int nameLength) {
- buffer.get(nameOffset, nameThreadLocal, 0, nameLength);
- return new String(nameThreadLocal, 0, nameLength, StandardCharsets.UTF_8);
+ private String parseName(MemorySegment memory, int nameOffset, int nameLength) {
+ byte[] array = memory.asSlice(nameOffset, nameLength).toArray(ValueLayout.JAVA_BYTE);
+ return new String(array, StandardCharsets.UTF_8);
}
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2026-05-13 14:51:35 +0000