[GitHub] [kafka] cmccabe commented on a change in pull request #9736: Add configurable workloads and E2E latency tracking to Trogdor.

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cmccabe commented on a change in pull request #9736:
URL: https://github.com/apache/kafka/pull/9736#discussion_r541379098



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File path: tools/src/main/java/org/apache/kafka/trogdor/workload/GaussianTimestampRandomPayloadGenerator.java
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@@ -0,0 +1,135 @@
+/*
+ * 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.trogdor.workload;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import org.apache.kafka.common.utils.Time;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Random;
+
+/**
+ * This class behaves identically to TimestampRandomPayloadGenerator, except the message size follows a gaussian
+ * distribution.
+ *
+ * This should be used in conjunction with TimestampRecordProcessor in the Consumer to measure true end-to-end latency
+ * of a system.
+ *
+ * `messageSizeAverage` - The average size in bytes of each message.
+ * `messageSizeDeviation` - The standard deviation to use when calculating message size.
+ * `timestampBytes` - The amount of bytes to use for the timestamp.  Usually 8.
+ * `messagesUntilSizeChange` - The number of messages to keep at the same size.
+ * `seed` - Used to initialize Random() to remove some non-determinism.
+ *
+ * Here is an example spec:
+ *
+ * {
+ *    "type": "gaussianTimestampRandom",
+ *    "messageSizeAverage": 512,
+ *    "messageSizeDeviation": 100,
+ *    "timestampBytes": 8,
+ *    "messagesUntilSizeChange": 100
+ * }
+ *
+ * This will generate messages on a gaussian distribution with an average size each 512-bytes and the first 8 bytes
+ * encoded with the timestamp.  The message sizes will have a standard deviation of 100 bytes, and the size will only
+ * change every 100 messages.  The distribution of messages will be as follows:
+ *
+ *    The average size of the messages are 512 bytes.
+ *    ~68% of the messages are between 412 and 612 bytes
+ *    ~95% of the messages are between 312 and 712 bytes
+ *    ~99% of the messages are between 212 and 812 bytes
+ */
+
+public class GaussianTimestampRandomPayloadGenerator implements PayloadGenerator {
+    private final int messageSizeAverage;
+    private final int messageSizeDeviation;
+    private final int timestampBytes;
+    private final int messagesUntilSizeChange;
+    private final long seed;
+
+    private final Random random = new Random();
+    private final ByteBuffer buffer;
+
+    private int messageTracker = 0;
+    private int messageSize = 0;
+
+    @JsonCreator
+    public GaussianTimestampRandomPayloadGenerator(@JsonProperty("messageSizeAverage") int messageSizeAverage,
+                                                   @JsonProperty("messageSizeDeviation") int messageSizeDeviation,
+                                                   @JsonProperty("timestampBytes") int timestampBytes,

Review comment:
       it would be good to have a default for timestampBytes, I think.  Basically if this gets set to 0, set it to 8 instead?
   
   Also, when would we want to change the number of timestamp bytes?




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