1 brc - 2gb memory 1 min 31 secs

calculate_average_abfrmblr.sh

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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 -Xms2g -Xmx2g"
+time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_abfrmblr

src/main/java/dev/morling/onebrc/CalculateAverage_abfrmblr.java

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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.util.concurrent.*;
+import java.util.stream.Stream;
+
+import static java.nio.file.Files.lines;
+import static java.nio.file.Paths.*;
+
+public class CalculateAverage_abfrmblr {
+
+    private static final String FILE = "./measurements.txt";
+
+    private static record Stats (double min, double max, double mean, long count) {
+        @Override
+        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 record MeasurementTuple (String station, double temp) {
+        public MeasurementTuple (String[] values) {
+            this(values[0], Double.parseDouble(values[1]));
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        Stream<String> lines = lines(get(FILE));
+
+        ConcurrentMap<String, Stats> aggregatedStats = new ConcurrentSkipListMap<>();
+
+        lines.parallel().forEach(s -> {
+            MeasurementTuple tuple = new MeasurementTuple(s.split(";"));
+            aggregatedStats.compute(tuple.station(), (s1, stats) -> {
+                if (stats == null) {
+                    return new Stats(tuple.temp, tuple.temp, tuple.temp, 1L);
+                }
+                else {
+                    long latestCount = stats.count + 1;
+                    double min = Math.min(stats.min, tuple.temp);
+                    double max = Math.max(stats.max, tuple.temp);
+                    double mean = ((stats.mean * stats.count) + tuple.temp) / latestCount;
+                    return new Stats(min, max, mean, latestCount);
+                }
+            });
+        });
+
+        System.out.println(aggregatedStats);
+
+    }
+
+}