Samrat002 commented on code in PR #28427: URL: https://github.com/apache/flink/pull/28427#discussion_r3610979649
########## flink-core/src/main/java/org/apache/flink/core/plugin/MetricsAware.java: ########## @@ -0,0 +1,49 @@ +/* + * 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.flink.core.plugin; + +import org.apache.flink.annotation.PublicEvolving; +import org.apache.flink.metrics.MetricGroup; + +/** + * Opt-in capability marker for {@link Plugin}s that register Flink metrics. Plugins that do not + * implement it emit no metrics; the hook is reusable by any plugin family, not only file systems. + * + * <p><b>Two-phase init.</b> The runtime calls {@link #setMetricGroup(MetricGroup)} after {@link + * Plugin#configure(org.apache.flink.configuration.Configuration)} and before any metric is emitted, + * only from entrypoints that own a process-level {@link MetricGroup} (TaskManager, JobManager) via + * {@link org.apache.flink.core.fs.FileSystem#attachMetrics(MetricGroup)}. Other contexts (CLI, + * HistoryServer, YARN client) never call it, and the plugin must keep working without metrics. + * + * <p><b>Idempotency.</b> {@code setMetricGroup} may be called more than once: the same {@link + * MetricGroup} must not register duplicate metrics, and a different group re-scopes metrics created Review Comment: > Would it produce log noise on attempts to register duplicate groups? No > Can we maybe give a simple example of why it can be called more than once? An embedded runtime may restart in the same JVM while retaining plugin instances. This does not produce duplicate-registration warnings in the built-in path. The real metric group returns its existing named child, and the native S3 factory treats re-applying that same group as a no-op. A replacement group only scopes metrics created afterwards. ########## flink-core/src/main/java/org/apache/flink/core/plugin/MetricsAware.java: ########## @@ -0,0 +1,49 @@ +/* + * 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.flink.core.plugin; + +import org.apache.flink.annotation.PublicEvolving; +import org.apache.flink.metrics.MetricGroup; + +/** + * Opt-in capability marker for {@link Plugin}s that register Flink metrics. Plugins that do not + * implement it emit no metrics; the hook is reusable by any plugin family, not only file systems. + * + * <p><b>Two-phase init.</b> The runtime calls {@link #setMetricGroup(MetricGroup)} after {@link + * Plugin#configure(org.apache.flink.configuration.Configuration)} and before any metric is emitted, + * only from entrypoints that own a process-level {@link MetricGroup} (TaskManager, JobManager) via + * {@link org.apache.flink.core.fs.FileSystem#attachMetrics(MetricGroup)}. Other contexts (CLI, + * HistoryServer, YARN client) never call it, and the plugin must keep working without metrics. + * + * <p><b>Idempotency.</b> {@code setMetricGroup} may be called more than once: the same {@link + * MetricGroup} must not register duplicate metrics, and a different group re-scopes metrics created Review Comment: > Would it produce log noise on attempts to register duplicate groups? No > Can we maybe give a simple example of why it can be called more than once? An embedded runtime may restart in the same JVM while retaining plugin instances. This does not produce duplicate-registration warnings in the built-in path. The real metric group returns its existing named child, and the native S3 factory treats re-applying that same group as a no-op. A replacement group only scopes metrics created afterwards. -- 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]
