[GitHub] [kafka] ijuma commented on a change in pull request #11721: KAFKA-13629: use faster algorithm for ByteUtils sizeOfXxx algorithm

[GitBox <gi...@apache.org>]

ijuma commented on a change in pull request #11721:
URL: https://github.com/apache/kafka/pull/11721#discussion_r798019651



##########
File path: jmh-benchmarks/src/main/java/org/apache/kafka/jmh/util/ByteUtilsBenchmark.java
##########
@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.kafka.jmh.util;
+
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.kafka.common.utils.ByteUtils;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@State(Scope.Thread)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+public class ByteUtilsBenchmark {
+    private static final int INPUT_COUNT = 10_000;
+    private static final int MAX_INT = 2 * 1024 * 1024;
+
+    private final int[] sizeOfInputs = new int[INPUT_COUNT];
+
+    @Setup(Level.Trial)
+    public void setUp() {
+        for (int i = 0; i < INPUT_COUNT; ++i) {
+            sizeOfInputs[i] = ThreadLocalRandom.current().nextInt(MAX_INT);
+        }
+    }
+
+    @Benchmark
+    public long testSizeOfUnsignedVarint() {
+        long result = 0;
+        for (final int input : sizeOfInputs) {
+            result += ByteUtils.sizeOfUnsignedVarint(input);
+        }
+        return result;
+    }
+
+    @Benchmark
+    public long testSizeOfUnsignedVarintOne() {
+        return ByteUtils.sizeOfUnsignedVarint(sizeOfInputs[0]);
+    }
+
+    @Benchmark
+    public long testSizeOfUnsignedVarintMath() {
+        long result = 0;
+        for (final int input : sizeOfInputs) {
+             int leadingZeros = Integer.numberOfLeadingZeros(input);
+             result += (38 - leadingZeros) / 7 + leadingZeros / 32;
+        }

Review comment:
       Do we want to remove the benchmark methods that include loops and rely on the ones without loops?




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