bbejeck commented on code in PR #17021: URL: https://github.com/apache/kafka/pull/17021#discussion_r1746160929
########## streams/src/main/java/org/apache/kafka/streams/internals/metrics/StreamsThreadDelegatingMetricsReporter.java: ########## @@ -0,0 +1,87 @@ +/* + * 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.streams.internals.metrics; + +import org.apache.kafka.clients.consumer.Consumer; +import org.apache.kafka.common.metrics.KafkaMetric; +import org.apache.kafka.common.metrics.MetricsReporter; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.List; +import java.util.Map; +import java.util.Objects; + +public class StreamsThreadDelegatingMetricsReporter implements MetricsReporter { + + + private static final Logger LOG = LoggerFactory.getLogger(StreamsThreadDelegatingMetricsReporter.class); + private Consumer<?, ?> consumer; + final String threadId; + final String stateUpdaterThreadId; + private static final String THREAD_ID_TAG = "thread-id"; + + + public StreamsThreadDelegatingMetricsReporter(final Consumer<?, ?> consumer, final String threadId, final String stateUpdaterThreadId) { + this.consumer = Objects.requireNonNull(consumer); + this.threadId = Objects.requireNonNull(threadId); + this.stateUpdaterThreadId = Objects.requireNonNull(stateUpdaterThreadId); + LOG.debug("Creating MetricsReporter for threadId {} and stateUpdaterId {}", threadId, stateUpdaterThreadId); + } + + @Override + public void init(final List<KafkaMetric> metrics) { + metrics.forEach(this::metricChange); + } + + @Override + public void metricChange(final KafkaMetric metric) { + if (tagMatchStreamOrStateUpdaterThreadId(metric)) { + LOG.debug("Registering metric {}", metric.metricName()); + consumer.registerMetric(metric); + } + } + + boolean tagMatchStreamOrStateUpdaterThreadId(final KafkaMetric metric) { + final Map<String, String> tags = metric.metricName().tags(); + final boolean shouldInclude = tags.containsKey(THREAD_ID_TAG) && (tags.get(THREAD_ID_TAG).equals(threadId) || tags.get(THREAD_ID_TAG).equals(stateUpdaterThreadId)); + if (!shouldInclude) { + LOG.warn("Rejecting metric {}", metric.metricName()); + } + return shouldInclude; + } + + @Override + public void metricRemoval(final KafkaMetric metric) { + if (tagMatchStreamOrStateUpdaterThreadId(metric)) { + LOG.info("Unregistering metric {}", metric.metricName()); + consumer.unregisterMetric(metric); + } + } + + @Override + public void close() { + this.consumer = null; Review Comment: Kafka Streams fully controls the consumer's life cycle, so calling close at this point would lead to unexpected behavior. Setting the consumer to `null` here prevents memory leaks by maintaining a reference to the embedded consumer. However, Kafka Streams does call `Metrics.close` on shutdown, which calls close on all reporters, so I suspect that won't be a problem - I'll leave as is for now. EDIT: I've taken another look and decided to remove setting the consumer to null here, even though I don't think it would be an issue with `Metrics.close` being called after Kafka Streams closes the consumer, better safe than sorry. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
