[GitHub] [nifi] markap14 commented on a change in pull request #5533: NIFI-9382: Created a new ClassloaderIsolationKey mechanism by which H…

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markap14 commented on a change in pull request #5533:
URL: https://github.com/apache/nifi/pull/5533#discussion_r752536616



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File path: nifi-api/src/main/java/org/apache/nifi/components/ClassloaderIsolationKey.java
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@@ -0,0 +1,60 @@
+/*
+ * 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.nifi.components;
+
+import org.apache.nifi.context.PropertyContext;
+
+/**
+ * <p>
+ * There are times when a component must be created in such a way that each instance gets its own ClassLoader hierarchy,
+ * rather than sharing the ClassLoader with other components (see {@link org.apache.nifi.annotation.behavior.RequiresInstanceClassLoading @RequiresInstanceClassLoading}).
+ * This, however, can be extremely expensive, as all of the classes must be loaded again for each instance of the component. When thousands of these
+ * components are used in a single flow, the startup time can be great, and it can lead to massive amounts of RAM being required.
+ * </p>
+ *
+ * <p>
+ * For components that do require instance ClassLoading that clones ancestor resources, this interface can be optional implemented by the component.
+ * If the interface is implemented, the component is given the opportunity to return a distinct "key" that can be used to identify instances that may share
+ * the same ClassLoader.
+ * </p>
+ */
+public interface ClassloaderIsolationKey {

Review comment:
       Fair enough. Will rename to `ClassloaderIsolationKeyProvider`




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