[GitHub] [pulsar] asafm commented on a diff in pull request #16758: [improve][txn] PIP-160 Metrics stats of Transaction buffered writer

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

asafm commented on code in PR #16758:
URL: https://github.com/apache/pulsar/pull/16758#discussion_r962312507


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pulsar-transaction/coordinator/src/main/java/org/apache/pulsar/transaction/coordinator/impl/TxnLogBufferedWriterMetricsStats.java:
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@@ -0,0 +1,208 @@
+/**
+ * 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.pulsar.transaction.coordinator.impl;
+
+import io.prometheus.client.CollectorRegistry;
+import io.prometheus.client.Counter;
+import io.prometheus.client.Histogram;
+import java.io.Closeable;
+import lombok.Getter;
+
+/***
+ * Describes the working status of the {@link TxnLogBufferedWriter}, helps users tune the thresholds of
+ * {@link TxnLogBufferedWriter} for best performance.
+ * Note-1: When batch feature is turned off, no data is logged at this. In this scenario，users can see the
+ *   {@link org.apache.bookkeeper.mledger.ManagedLedgerMXBean}.
+ * Note-2: Even if enable batch feature. A batch has numerous triggers. The metrics in this class count each type of
+ *   trigger to allow you to diagnose what mostly causing a batch flush. The metric also includes a histogram for delay
+ *   of batch since 1st record entered, the size of batch in bytes number of records in batch. This will help you to
+ *   tune the parameters that control some of the batch flush triggers: maxDelay, maxRecords, maxSize.
+ *   Note that the 4th trigger - a single record larger than batch size - triggers a flush of the current batch, but
+ *   the big record itself is not written in batch hence is not included in the batch metrics written above (batch
+ *   size, batch delay, etc). The trigger is of course counted as other trigger types.
+ */
+public class TxnLogBufferedWriterMetricsStats implements Closeable {
+
+    static final double[] RECORD_COUNT_PER_ENTRY_BUCKETS = {10, 50, 100, 200, 500, 1_000};
+
+    static final double[] BYTES_SIZE_PER_ENTRY_BUCKETS = {128, 512, 1_024, 2_048, 4_096, 16_384,
+            102_400, 1_232_896};
+
+    static final double[] MAX_DELAY_TIME_BUCKETS = {1, 5, 10};
+
+    @Getter
+    private final String metricsPrefix;
+
+    private final String[] labelNames;
+
+    private final String[] labelValues;
+
+    /** Count of records in per transaction log batch. **/
+    private final Histogram recordsPerBatchMetric;
+    private final Histogram.Child recordsPerBatchHistogram;
+
+    /** Bytes size per transaction log batch. **/
+    private final Histogram batchSizeBytesMetric;
+    private final Histogram.Child batchSizeBytesHistogram;
+
+    /** The time of the oldest transaction log spent in the buffer before being sent. **/
+    private final Histogram oldestRecordInBatchDelayTimeSecondsMetric;
+    private final Histogram.Child oldestRecordInBatchDelayTimeSecondsHistogram;
+
+    /** The count of the triggering transaction log batch flush actions by "batchedWriteMaxRecords". **/
+    private final Counter batchFlushTriggeredByMaxRecordsMetric;
+    private final Counter.Child batchFlushTriggeredByMaxRecordsCounter;
+
+    /** The count of the triggering transaction log batch flush actions by "batchedWriteMaxSize". **/
+    private final Counter batchFlushTriggeredByMaxSizeMetric;
+    private final Counter.Child batchFlushTriggeredByMaxSizeCounter;
+
+    /** The count of the triggering transaction log batch flush actions by "batchedWriteMaxDelayInMillis". **/
+    private final Counter batchFlushTriggeredByMaxDelayMetric;
+    private final Counter.Child batchFlushTriggeredByMaxDelayCounter;
+
+    /**
+     * If {@link TxnLogBufferedWriter#asyncAddData(Object, TxnLogBufferedWriter.AddDataCallback, Object)} accept a
+     * request that param-data is too large (larger than "batchedWriteMaxSize"), then two flushes are executed:
+     *    1. Write the data cached in the queue to BK.
+     *    2. Direct write the large data to BK.
+     * This ensures the sequential nature of multiple writes to BK.
+     */
+    private final Counter batchFlushTriggeredByLargeSingleDataMetric;
+    private final Counter.Child batchFlushTriggeredByLargeSingleDataCounter;
+
+    /**
+     * Users needs to ensure that the {@link TxnLogBufferedWriterMetricsStats} of the same {@param metricsPrefix} can
+     * only create once, otherwise an IllegalArgumentException will be thrown.
+     */
+    public TxnLogBufferedWriterMetricsStats(String metricsPrefix, String[] labelNames, String[] labelValues,

Review Comment:
   @tjiuming This is what I consulted with you if you remember a couple of weeks ago, and based on this I wrote: https://github.com/apache/pulsar/pull/16758#issuecomment-1207782630



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